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Journal of Lipid Research, Vol. 45, 1008-1026, June 2004
Copyright © 2004 by American Society for Biochemistry and Molecular Biology

Review

Genetics of LDL particle heterogeneity

Yohan Bossé^*,, Louis Pérusse and Marie-Claude Vohl^1,*,

^* Lipid Research Center, Laval University Medical Research Center, Laval University, Québec, Canada
Department of Food Science and Nutrition, Laval University, Québec, Canada
Division of Kinesiology, Department of Social and Preventive Medicine, Laval University, Québec, Canada

Published, JLR Papers in Press, April 1, 2004. DOI 10.1194/jlr.R400002-JLR200

¹ To whom correspondence should be addressed. e-mail: marie-claude.vohl{at}crchul.ulaval.ca

	ABSTRACT

TOP ABSTRACT INTRODUCTION GENETIC EPIDEMIOLOGY DNA-BASED VARIANTS COMPLEMENTARY GENETIC APPROACHES CONCLUSION REFERENCES

 
Substantial evidence exists suggesting that small, dense LDL particles are associated with an increased risk of coronary heart disease. This disease-related risk factor is recognized to be under both genetic and environmental influences. Several studies have been conducted to elucidate the genetic architecture underlying this trait, and a review of this literature seems timely. The methods and strategies used to determine its genetic component and to identify the genes have greatly changed throughout the years owing to the progress made in genetic epidemiology and the influence of the Human Genome Project. Heritability studies, complex segregation analyses, candidate gene linkage and association studies, genome-wide linkage scans, and animal models are all part of the arsenal to determine the susceptibility genes. The compilation of these studies clearly revealed the complex genetic nature of LDL particles.

This work is an attempt to summarize the growing evidence of genetic control on LDL particle heterogeneity with the aim of providing a concise overview in one read.

Abbreviations: apoB, apolipoprotein B; BMI, body mass index; CAD, coronary artery disease; CETP, cholesteryl ester transfer protein; CHD, coronary heart disease; DGU, density gradient ultracentrifugation; DZ, dizygotic; FATP1, fatty acid transport protein-1; FCHL, familial combined hyperlipidemia; GET, Genetic Epidemiology of Hypertriglyceridemia; GGE, gradient gel electrophoresis; HDL-C, high density lipoprotein cholesterol; LDL-PPD, low density lipoprotein peak particle diameter; LDLR, low density lipoprotein receptor; LDL-Rf, low density lipoprotein flotation rate; LOD, logarithm of the odds; MTP, microsomal triglyceride transfer protein; MZ, monozygotic; QFS, the Québec Family Study; QTL, quantitative trait locus; RFLP, restriction fragment length polymorphism; SOD2, manganese superoxide dismutase; SR-BI, scavenger receptor class B type I

Supplementary key words low density lipoprotein size • heritability • inheritance • linkage study • association study • genome scan

	INTRODUCTION

TOP ABSTRACT INTRODUCTION GENETIC EPIDEMIOLOGY DNA-BASED VARIANTS COMPLEMENTARY GENETIC APPROACHES CONCLUSION REFERENCES

 
LDL cholesterol is a well-known risk factor for coronary heart disease (CHD) and is now recognized as the primary target of lipid-lowering therapy (1). However, it is known that LDL particles are heterogeneous in terms of size, density, chemical composition, and electric charge (2–4). Data from case-control (5) and prospective (6–9) studies have suggested that small, dense LDL particles are associated with increased risk of CHD. The atherogenicity of these particles is attributed to several possible biological mechanisms, including greater susceptibility to oxidation (10–14), decreased affinity for the LDL receptor (15–19), increased binding to the arterial wall (20–23), and greater facility to cross the arterial wall (24, 25) as well as having negative effects on the endothelium function (26). Additional evidence for the relevance of the small, dense LDL on atherosclerotic lesion development and CHD progression is derived from an animal model (27) and lipid-lowering trials in humans (28, 29). On the other hand, recent findings from the Cholesterol and Recurrent Events trial (30) support earlier case-control (31–34) and prospective (35) studies showing that small, dense LDLs are not risk factors for CHD. In fact, some of these studies have shown that larger LDL particles are associated with CHD. Although these studies disagree on which LDL particle size (small or large) is related to CHD risk (36), defining the genetic and environmental factors that modulate LDL particle properties may be helpful in understanding its relationship with CHD.

Multiple approaches have been used to determine the genes involved in complex human diseases and disease-related risk factors. Through the years, methods and strategies have evolved following the progress made in genetic epidemiology and the completion of the Human Genome Project. Genetic studies on LDL particles represent a perfect example of this phenomenon. Several studies have investigated the genetics of LDL particle heterogeneity. Heritability studies, complex segregation analyses, linkage and association studies with candidate genes, and genome-wide linkage scans are all part of the arsenal used to dissect the genetic architecture of this trait. Cumulative evidence is growing rapidly, and a review of these studies seems timely.

Several studies have shown that small, dense LDLs are associated with a constellation of other well-recognized lipoprotein-related risk factors, including increased plasma triglyceride and apolipoprotein B (apoB) levels as well as decreased HDL cholesterol concentrations. Furthermore, small, dense LDL particles coexist in the same subjects as part of multifaceted phenotypes, including the metabolic syndrome, the atherogenic lipoprotein phenotype (LDL subclass pattern B), and familial combined hyperlipidemia (FCHL) (37). Thus, small, dense LDL may be a qualitative trait representing a common atherogenic lipoprotein/metabolic profile, and the proposed genetic loci responsible for small, dense LDL may in fact be responsible for a more extensive syndrome. However, throughout this review, we have chosen to adopt a more narrow view on the phenotypes that characterize LDL particle heterogeneity. These phenotypes are the central focus of this paper, and we summarize the published genetic studies surrounding them.

A number of analytical techniques are available for characterizing LDL heterogeneity, and it is beyond the scope of the present paper to describe them in detail. However, some technicality must be addressed before going through genetic ground. LDL heterogeneity was first described using analytical ultracentrifugation (38). Over the years, this technique was replaced by others, including density gradient ultracentrifugation (DGU), gradient gel electrophoresis (GGE), and, more recently, NMR spectroscopy. The phenotypes derived from these techniques are those used in the genetics studies performed to date. Based on GGE, a continuous variable can be defined as LDL peak particle diameter (LDL-PPD), reflecting the size of the major LDL subclass in an individual subject. A dichotomous classification can also be defined based on GGE; it is referred to as LDL subclass patterns, or phenotypes, A and B. LDL subclass phenotype A is characterized by a predominance of large LDL particles and skewing of the densitometric scan toward small particles, whereas LDL subclass phenotype B is characterized by a predominance of small LDL particles and skewing of the curve toward large particles (39). Other phenotypes can be constructed using GGE, including LDL score, which is calculated using the migration distance (in millimeters) of each peak multiplied by its respective relative area (40), and LDL type, which is a weighted average of seven possible categories of LDL, resulting in a variable ranging from 1 (largest) to 7 (smallest) (41). For a detailed description of these techniques, the reader is referred to previously published reviews (5, 42, 43).

	GENETIC EPIDEMIOLOGY

TOP ABSTRACT INTRODUCTION GENETIC EPIDEMIOLOGY DNA-BASED VARIANTS COMPLEMENTARY GENETIC APPROACHES CONCLUSION REFERENCES

 
Familial aggregation
The first evidence for a genetic determination of LDL properties was reported by Fisher et al. in 1975 (44). Five families, including 11 couples and 16 offspring, were examined for their LDL molecular weights. Only subjects having monodisperse LDL (i.e., LDL that is found to be present as a single, essentially homogeneous population of macromolecules) were included in the study. Correlation coefficients between pairs of relatives revealed a significant parent-offspring correlation (0.82; P < 0.01) but absence of correlation between fathers and mothers (0.32; P = NS). These results provided evidence for the genetic contribution of LDL molecular weight. To further determine the degree of resemblance of the offspring to their parents, a regression coefficient of the mean molecular weight of the offspring on the mean parental molecular weight was calculated. The regression coefficient was 0.30 (P < 0.01), which made the authors conclude that 30% of the observed LDL molecular weight variance is attributable to additive gene action. In addition, based on the five families, the authors postulated a model consistent with a single-gene (two-allele) locus genetic mode of inheritance without dominance. Although the sample size used in this study was relatively small, it demonstrated for the first time that LDL characteristics segregate within families.

Since this earlier report, accumulating evidence of familial and ethnic aggregation of LDL subclasses has emerged in the literature. Haffner et al. (45, 46) demonstrated a significant difference between ethnic groups in LDL size among 1,571 subjects from the Insulin Resistance Atherosclerosis Study and 466 subjects from the San Antonio Family Heart Study. These studies cannot distinguish the effect of the genetic background from the effect mediated by the difference in lifestyles between ethnic groups, but they clearly motivated genetic studies in the field. More recently, the familial resemblance of LDL-PPD was evaluated in 681 individuals participating in the Québec Family Study (QFS) (47). An ANOVA comparing between-family and within-family variance indicated that there was approximately two times more variance between families than within families. Thus, results from the QFS suggested that the family lines accounted for close to 50% (47–49% depending on covariate adjustment) of the variance in LDL-PPD phenotype. In addition, the pattern of familial correlations revealed no spouse correlation but significant parent-offspring and sibling correlations for the LDL-PPD phenotypes, suggesting that genetic factors are the major determinants of the familial aggregation. The same pattern of correlations was observed among Finnish families with FCHL (48).

Heritability analysis
Twin studies Studies using identical [monozygotic (MZ)] and fraternal [dizygotic (DZ)] twins have been used to assess the heritability of LDL size (Table 1). The first study on this issue was based on 119 MZ and 113 DZ twin pairs participating in the third examination of the National Heart, Lung, and Blood Institute Twin Study (49). In this study, the LDL subfractions were separated by GGE and the heritability analysis used LDL type. The LDL type intraclass correlation coefficient in MZ twins was significantly higher than the correlation coefficient in DZ twins (0.58 vs. 0.32; P < 0.005), with a heritability of 0.52 before controlling for covariate effects. After adjustment for body mass index (BMI), alcohol consumption, cigarette smoking, and physical activity, the heritability decreased to 0.39. Despite being of great magnitude, these estimates were not statistically significant, suggesting the lack of heritability for LDL type. Similar results were obtained when only the major LDL band (LDL-PPD) was used as a variable. Thus, the authors concluded that LDL particle size is not greatly influenced by genetic factors within this population. It is noteworthy that the authors used the more conservative among-component (50) estimate of heritability because there was some indication of unequal total variance between zygosities. Although this procedure is considered more suitable in such cases, the power to detect significant heritability is substantially reduced.

Family studies Heritability estimates of LDL-PPD were also evaluated using family data. The first family study on this issue was based on 780 individual members of 85 families participating in the Genetic Epidemiology of Hypertriglyceridemia (GET) Study (52). The GET Study is based on two family studies, one ascertained through hyperlipidemic probands surviving a myocardial infarction and the second through hypertriglyceridemic probands without CHD. After accounting for age and sex effects, results suggested that approximately one-third of the residual variance in LDL-PPD (heritability = 0.34) was attributable to additive genetic effects. The heritability estimate for LDL-PPD from the QFS was slightly higher (47). In this study, three LDL-PPD phenotypes based on three different adjustment procedures were constructed: LDL-PPD1 adjusted for age, LDL-PPD2 adjusted for age and BMI, and LDL-PPD3 adjusted for age, BMI, and triglyceride levels. Heritability estimates for the three phenotypes were 58.8, 58.4, and 52.0%, respectively. The high heritabilities obtained may be explained by the design of the study. Indeed, in this case, heritability is defined as the proportion of variance attributable to additive familial effects, including both genetic and nongenetic sources of variance. Although the pattern of familial correlations in the QFS suggested that the familial resemblance is mostly attributable to genetic factors, heritability estimates derived from this cohort may be considered as the upper bound estimates for LDL-PPD. High heritability coefficients were also observed for LDL size in Ashkenazi Jewish families ascertained for exceptional longevity (53). In this study, LDL size was characterized by NMR, and heritability was estimated at 0.46 in women and 0.60 in men. These results demonstrated that LDL size is highly heritable irrespective of the analytical methods used to characterize the particles and suggested that the measurement error inherent in each technique does not mask the genetic signal.

By means of a new metric representing coordinated size variation between HDL and LDL particles, Rainwater, Martin, and Comuzzie (54) conducted an original study to test the hypothesis that there are "lipoprotein size genes." The new metric, named LDL, is a metric for LDL particle size phenotype that optimally reflects the size correlation between LDL and HDL particles. LDL was subjected to quantitative genetic analyses using 1,157 Mexican Americans participating in the San Antonio Family Heart Study. The heritability of LDL was highly significant and indicated that nearly half (44%) of the residual variance (after adjustment for sex, age, diabetes status, contraceptive use, and hypertension medications) in LDL was explained by additive gene effects. After including triglyceride levels in the model as a covariate, the heritability estimate decreased from 0.44 to 0.30, indicating gene(s) common for both traits. These data indicate that particle size phenotypes are under substantial genetic control.

Taken together, the above studies suggested that 30% to 60% of the variance in LDL particle size is attributable to genetic factors, with the remainder attributable to nongenetic influences. Accordingly, these genetic studies also indicated the importance of nongenetic factors on LDL subclasses, because 50% of the variance is attributable to nongenetic factors. A number of environmental influences have been identified, including dietary factors (55), physical activity (56), abdominal obesity (57), and insulin resistance and hyperinsulinemia (58). The combination of genetic and environmental influences provides opportunities to develop prevention strategies to reduce CHD risk among genetically susceptible individuals (59).

Inheritance of the LDL heterogeneity: testing for a single-gene effect
Heritability estimates obtained from twin and family studies reinforced the interest in finding gene(s) underlying that genetic effect. Below, we describe the different lines of evidence that proved the existence of a single gene with a major effect on the phenotype, including commingling analyses, segregation analyses, and complex segregation analyses.

Commingling analyses Commingling analyses are often used as a preliminary method to screen for the presence of a single gene with a major effect (60). In the presence of such a gene, the distribution of a quantitative phenotype is better characterized by a mixture of distributions than by a single distribution. An analysis of the LDL-PPD distribution in the Kaiser Permanente Women Twins Study identified three distinct subgroups of subjects (51). Indeed, a trimodal model provided a better fit to the data compared with a bimodal or a unimodal model. A trimodal model was also reported for the age- and gender-adjusted LDL-PPD distribution in a sample of healthy families from a Mormon community (61). Finally, in 373 family members of Israel origin, the mixture of two normal distributions for age- and gender-adjusted LDL-PPD fit the data significantly better than a single distribution (62). However, the trimodal model could not be rejected over the bimodal model. Taken together, results from commingling analyses are compatible with the presence of a major gene effect affecting LDL-PPD. However, this pattern of distribution may also arise as a result of nongenetic factors. Thus, any inference drawn from these studies needs to be interpreted with caution.

Segregation analyses The first studies that investigated the inheritance of LDL heterogeneity were derived from fitting the data into pedigrees under a hypothetical genetic mode (Table 2). Fisher et al. (44) were the first to provide evidence for a single-gene, two-allele system locus affecting LDL heterogeneity. Using pedigrees from five families, they proposed a model of two alleles, one a determinant for high, the other for low, LDL molecular weight. A decade later, Austin and Krauss (63) evaluated the lipoprotein subclasses (pattern A/B) by GGE in 79 healthy members of 16 nuclear families living in a local Mormon community. Their data proposed a genetic model consistent with a single-locus, two-allele system as well. The estimated frequency of the allele leading to the phenotype characterized by a predominance of small, dense LDL subclasses (pattern B) was 15% under a dominant mode of inheritance. However, in contrast to the observation of Fisher et al. (44), expression of the phenotype appears to be age dependent in that most affected subjects in the population were older than 40 years. Although different techniques were used to detect LDL properties between these two studies, it is possible that the LDL pattern reported in the latter study and the molecular weight reported in the former study represent the same trait. Although these studies were limited by their sample size, they provided additional evidence in favor of a single gene affecting LDL density and size.

The two later complex segregation studies were based on the dichotomization of the LDL subfraction into two discrete phenotypes. It is possible that this dichotomous definition oversimplifies the biochemical heterogeneity of LDL particles. de Graaf et al. (66) were concerned by such a procedure because much information is lost, i.e., we do not know whether an individual is close to or far from the LDL size threshold for the pattern A/pattern B classification, which results in a loss of power (67). Accordingly, they constructed a continuous variable, named parameter K, that reflects LDL subfraction profile and that is characterized by the relative contribution of the three major LDL subfractions (LDL-1, LDL-2, and LDL-3) determined by DGU. Analysis for this quantitative trait was performed on 19 healthy Dutch families including 159 individuals. Results indicated that the LDL subfraction profile is controlled by a major autosomal, highly penetrant recessive allele with a population frequency of 19% and an additional multifactorial inheritance component. The penetrance of the more dense LDL allele increases with age for both sexes but was higher for men than for women. Furthermore, it appeared that oral contraceptive use was associated with a high penetrance of the more dense LDL subfraction profile. Also concerned by the possibility that the dichotomous trait may not provide the best reflection of LDL size distribution, Austin et al. (61) reanalyzed their healthy subjects living in a Mormon community, this time using LDL-PPD instead of the dichotomous classification reported earlier (64). The model providing the best fit to the data consisted of a single major gene effect with Mendelian inheritance and with no additional multifactorial inheritance component. However, the available sample was not sufficient to distinguish dominant versus recessive mode of inheritance. Thus, analysis of the continuous LDL-PPD variable was not superior to the dichotomous LDL subclass pattern classification in determining the mode of inheritance of LDL subclasses in this healthy sample of families. The mode of inheritance of parameter K was also investigated in a large sample of Dutch families with FCHL (68). The genetic basis of LDL subfraction profile in these families was best described by a common, major autosomal gene effect with a population frequency of 42% and a recessive mode of inheritance with a polygenic heritability component of 25%. Subsequently, the mode of inheritance of LDL-PPD was investigated in 373 subjects from 80 kindreds residing in kibbutz settlements in Israel (62). Complex segregation analyses of sex- and age-adjusted LDL-PPD were inconclusive in this study, because both the mixed recessive genetic model and the mixed environmental model could not be rejected. However, when the regression model for sex and age allowed coefficients to be ousiotype (genotype class) specific, the mixed environmental model was rejected and a major Mendelian model was not. Indeed, a major additive gene (codominant) model for LDL-PPD with an allele frequency of 24% for small LDL particles could not be rejected. In addition, this model contains a large polygenic component (74%). The authors postulated that the ethnic homogeneity and the lifestyle similarity of the sample may explain the high contribution of polygenic factors to LDL-PPD. More recently, the genetic influence of LDL-PPD was modeled in 48 Finnish FCHL families (48). Complex segregation analyses in these families suggested that the trait is the result of the additive effects of multiple genes in which a recessive major gene effect of low frequency (6%) may contribute to large LDL-PPD in women. For men, the authors could not establish that LDL-PPD follows a strictly polygenic model, but the results indicated that LDL size is unlikely to be influenced by a major gene effect in this population.

With the exception of the latter study, results from complex segregation analyses support the concept of a major gene effect involved in LDL size and density. However, some dissimilarities were found between the studies with regard to the mode of inheritance, allele frequency, and the presence or absence of a multifactorial inheritance component. This discrepancy could be explained by differences in family structures, criteria for proband ascertainment, and the use of different techniques to characterize LDL heterogeneity. Nevertheless, these studies unanimously provided evidence about the contribution of a major gene effect and clearly motivate the race to find it.

	DNA-BASED VARIANTS

TOP ABSTRACT INTRODUCTION GENETIC EPIDEMIOLOGY DNA-BASED VARIANTS COMPLEMENTARY GENETIC APPROACHES CONCLUSION REFERENCES

 
Linkage studies
Many investigators have used linkage analyses to identify the genes underlying the genetic contribution of LDL particle characteristics. The early studies were performed using candidate gene strategies by studying genetic variations located within or in proximity to genes coding protein products known to be involved in lipoprotein/lipid metabolism. On the other hand, recent studies have used a genome-wide scan approach to identify chromosomal regions influencing LDL size-related phenotypes. Table 3 presents a summary of the loci and genes, ordered by chromosome number, that have provided evidence of linkage using these two strategies. It should be noted that only positive findings are provided in this table, and careful examination of the literature might in fact show significant evidence against linkage for certain loci presented. It is also worth mentioning that opposite results for the same gene may not necessarily imply controversy, given the different study samples.

Taken together, linkage studies based on the candidate gene approach have provided positive but mainly inconsistent results. Based on these observations, Austin et al. (75) emphasized the necessity of finding new genetic loci, other than those harboring known candidate genes, to identify genes potentially involved in determining the small, dense LDL phenotype. Genome-wide scans are particularly suited for this purpose. To date, three genome-wide linkage scans have been reported in the literature for LDL-PPD. Results of these genome-wide searches are indicated in boldface in Table 3 and are illustrated in Fig. 1 . The first whole-genome scan on LDL-PPD was performed on 240 individuals ascertained through 18 unrelated FCHL probands (78). The results suggested a locus located 12 Mb from the HL gene on chromosome 15 with a LOD score of 2.2. Suggestive linkage (LOD = 1.6) was also observed for a marker located on chromosome 19q13, which contains the APOE-CII-CI gene cluster. The second genome scan was carried out in 681 subjects from 236 nuclear families participating in the QFS (80). The strongest evidence of linkage was found on chromosome 17q23, with a LOD score of 6.76 for the phenotype adjusted for age, BMI, and triglyceride levels. The APOH gene is a particularly interesting candidate gene in this area. Other chromosomal regions provided LOD greater than 2.0, including 1p33-p31, 2q33-q36, 4p15-q13, 5q13-q14, and 14q23-q32. Although this genome scan gives strong evidence for the presence of a major quantitative trait locus (QTL) located on 17q, it also demonstrated the multilocus nature of LDL size. The third genome scan on LDL-PPD was based on 140 subjects from 26 hypertriglyceridemia families participating in the GET Study (81). For the whole-genome scan, only one chromosomal region provided possible evidence of linkage on chromosome 6q (LOD = 2.1). When the LDL-PPD was adjusted for other lipoprotein covariates, the LOD score decreased slightly but the location of the peak remained unchanged, suggesting that the signal is independent of other lipoprotein levels. The SOD2 and apo[a] genes are located within the one LOD score support interval. An additional genome scan of cholesterol concentrations within LDL size subfractions is also worth mentioning. Rainwater et al. (82) found two QTLs on chromosomes 3 and 4 with LOD scores greater than 3 for LDL size 3 (LDL-3), a subfraction that contains small LDL particles. Suggestive linkage was also observed on 3p26-p25 and 6q24-q27 for LDL-3, 19p13-q12 for LDL-1 (a subfraction that contains large particles), and 19q13 for LDL-2 (a subfraction that contains particles of intermediate diameter). This study evaluated LDL size-related phenotypes, but QTLs identified are those affecting the cholesterol concentration within a particular subpopulation of LDL and do not correspond to QTLs affecting the size of the particles.

View larger version (45K): [in this window] [in a new window]   Fig. 1. Ideogram of human karyotype showing chromosomal locations of genes and quantitative trait loci (QTLs) potentially involved in LDL size/density identified from various lines of evidence reviewed in this article. Only positive findings are included (see text for the complete results). Red and purple lines indicate QTLs identified by genome-wide linkage scans in humans and animals, respectively. Genes linked (green rectangles), associated (yellow rectangles), or both linked and associated (blue rectangles) to LDL particle characteristics are shown. Genes and QTLs are placed on the hybrid map showing the sequence and the cytogenetic locations. Information to construct the

Association studies
A considerable number of association studies have been conducted to identify the genes influencing LDL particle characteristics. Table 4 presents a summary of these studies organized by genes and ordered by chromosome number.

HL The human HL gene is located on chromosome 15q and encodes a protein that plays an important role in lipoprotein metabolism. Two polymorphisms, –250G>A and –514C>T (also referred to as –480C>T), have been tested with LDL particle size/density. These two polymorphisms are in linkage disequilibrium (92), and the rare allele is associated with lower HL activity (93, 94). Zambon et al. (93) were the first to describe an association between the –250G>A polymorphism and LDL particle flotation rate (LDL-Rf) measured by DGU. They have shown that the less common A allele was associated with more buoyant LDL particles among normolipidemic subjects and men with CAD. This finding was then replicated in a group of premenopausal women showing more buoyant LDL particles among carriers of the T-514 allele (94). However, a larger study, conducted in 2,667 subjects participating in the Framingham Offspring Study, found no relationship between HL polymorphism at position –514 and the LDL particle size measured by GGE (95). This lack of association between this variant and LDL size measured by GGE was also observed in a subgroup of unrelated subjects from FCHL Dutch families (78) and in a cohort of healthy, middle-aged men (85). The different methods used to characterize LDL particles might explain the inconsistency. However, an additional study rejected the hypothesis of association between the –514C>T polymorphism and LDL particle size measured by NMR (96).

CETP The CETP gene lies on chromosome 16q and encodes a protein that facilitates the exchange of triglyceride and cholesterol between lipoproteins. The LDL particles of CETP-deficient patients constitute a group of abnormal heterogeneous particles that show polydispersity on GGE with a smaller mean particle size (97). The most studied restriction fragment length polymorphism (RFLP) in this gene, Taq1B in intron 1, was associated with CETP activity and mass. In fact, the B2 allele (absence of the Taq1 restriction site) was associated with decreased CETP activity and mass, which mimics a mild form of CETP deficiency (94, 98). The Framingham Offspring Study again provided the largest population-based cohort (n = 2,916) investigating this polymorphic site with LDL size (98). This study reported that the B2 allele in men was associated with increased levels of the large LDL subfraction, whereas B1B1 homozygous subjects had increased levels of the small LDL subfraction. Therefore, the B2 allele was associated with increased LDL particle size, an effect seen only in men. The effect of the B2 allele was also observed in the Columbia University BioMarker Study, but this time only in women (96). In this study, women homozygous for the B2 allele had larger particles compared with carriers of the B1 allele. This difference was also observed in men, but the small number of men tested might have lacked the power to detect a significant effect. In contrast, the absence of association between the Taq1B polymorphism and LDL-Rf was reported in a cohort of normolipidemic premenopausal women (94). A trend toward greater LDL size with increasing numbers of B2 alleles was observed in the Veterans Affairs HDL Cholesterol Intervention Trial group, but the effect did not reach statistical significance (99). This lack of association was also observed in a cohort of patients with type 2 diabetes (100) and in Japanese subjects (101). However, a second polymorphism in the CETP gene, namely I405V, showed a significant association in this Japanese study. The authors demonstrated lower LDL size in patients with the VV genotype compared with carriers of the I allele. A significant effect of this polymorphism was also observed in families ascertained for exceptional longevity (53). However, in this cohort, subjects carrying the VV genotype had larger LDL particles. The latter study also reported no association between LDL size and a third gene variant in linkage disequilibrium with the Taq1B polymorphism named –629C>A. In contrast, carriers of the –629C>A polymorphism had increased LDL-PPD compared with CETP-629C homozygotes in a cohort of healthy, middle-aged men (85). Finally, a less frequent missense mutation, D442G in exon 15, in the CETP gene was investigated in patients with CAD. The presence of this mutation was associated with lower CETP concentrations and larger LDL size (102).

MTP The MTP gene, located on chromosome 4q, encodes a protein essential in the assembly and secretion of apoB-containing lipoproteins in hepatocytes and enterocytes. A common functional polymorphism in the promotor of the MTP gene, –493G>T, was investigated in relation to LDL particle size. Couture et al. (103) showed no association between the –493G>T genotype and LDL size in 2,510 subjects participating in the Framingham Offspring Study. This absence of association was also observed in a group of viscerally obese men (104). The only positive association between the –493G>T variant and LDL size was observed in a small sample of Chinese subjects with type 2 diabetes (105). The authors of this study reported smaller LDL particle size among TT homozygotes compared with the other genotypes.

LPL The LPL gene is located on chromosome 8p and encodes a protein that is responsible for the hydrolysis of triglyceride within apoB-containing lipoproteins. Several mutations have been identified in the LPL gene, and some of them have been associated with LDL particle size. First, a missense mutation at codon 188 causes a clear reduction in LPL activity. Carriers of this defective mutation had smaller LDL size compared with noncarrier family members (106). Similarly, lower LDL size was observed among carriers of the LPL Tyr302-Ter mutation in an Italian family (107). Hokanson et al. (77) confirmed the LDL size-reducing effect of LPL deficiency in five families with structural mutations in the LPL gene. Subsequently, the Ser447-Ter mutation in exon 9 was associated with larger LDL size (85, 108). This mutation causes a premature termination codon that, surprisingly, increases the enzymatic activity of LPL (85, 109). These observations suggested that the mutations that decrease LPL activity cause a reduction in LDL size and that the mutations that increase LPL activity increase LDL size. This hypothesis was confirmed in a cohort of 206 heterozygote subjects carrying either the null P207L or the defective D9N mutation (110). In this study, LDL particle size was smaller in the P207L carriers than in the D9N subjects, suggesting that a greater reduction in LPL activity results in smaller LDL particle size. However, this relation between LPL genetic variants, LPL activity, and LDL size is not without controversy, given that the greater LDL particle size observed among carriers of the Ser447-Ter mutation was not confirmed in the Columbia University BioMarkers Study (96).

APOA1/CIII/A4/A5 cluster The APOA1/CIII/A4/A5 cluster lies on chromosome 11q and encodes four proteins involved in lipoprotein metabolism. Genetic variations within individual genes have been associated with LDL particle characteristics. Russo et al. (111) tested the SstI polymorphism on the 3' untranslated region of the APOC3 gene and showed that male carriers of the S2 allele had significantly lower concentrations of large LDL and a significant reduction in LDL size. In women, there was no significant effect on LDL size. The other polymorphisms tested in the APOC3 gene (–455T>C, –625T>del, and C3238G) showed no association with LDL particle size (96, 112). However, the SacI and the –625T>del polymorphisms, located in the 3' untranslated and promotor regions of the APOC3 gene, respectively, were significantly associated with LDL charge (113). In contrast, the same study reported no association between APOA1 restriction sites (PstI and MspI) and LDL charge. Recently, Austin et al. (114) demonstrated, with several analytic approaches, that common single nucleotide polymorphism (SNP) variants in the APOA5 gene were associated with LDL particle size in a community-based sample of Japanese American families. This study particularly pinpointed the –3A>G variant to decrease LDL size. However, considering the close proximity of the four genes in the cluster, it is difficult to determine with certainty that the effect observed with one of them is mediated by the gene tested. Indeed, a positive finding in one gene might be attributable to linkage disequilibrium of the tested marker with a polymorphism in a second gene within the cluster. Accordingly, further studies in the APOA1/CIII/A4/A5 gene cluster will be required to identify the functional site.

Other candidate genes: APOB, cholesterol 7-hydroxylase, angiotensin-converting enzyme, ß3-adrenergic receptor, phox 22, fatty acid transport protein-1, scavenger receptor class B type I, LDLR, and ABCA1 One study verified the effect of the APOB EcoRI polymorphism in a group of Caucasian men and showed no effect on either LDL-PPD or LDL score (115). However, five polymorphisms in the APOB gene were found to influence LDL charge heterogeneity evaluated by relative electrophoretic mobility (113). A common A-to-C substitution at position –204 in the promoter of the cholesterol 7-hydrolase gene showed no association with LDL particle size (116). The hypothesis that the angiotensin-converting enzyme gene insertion/deletion polymorphism was associated with LDL size was also rejected in a small Japanese cohort (84). However, a recent paper suggested a positive association between the Trp64Arg variant in the ß₃-adrenergic receptor and LDL-PPD (117). The authors reported that the LDL particle size was smaller in subjects with the Arg64 allele than those without the Arg64 allele. The effect remained significant after triglyceride adjustment but disappeared after adjustment for BMI or parameters of insulin resistance. The phox 22 gene, which is a small subunit of vascular NAD(P)H oxidase that plays an important role in superoxide production, was also investigated in a group of healthy Japanese subjects (118). A trend (P = 0.08) toward larger LDL-PPD was observed among carriers of the C242T polymorphism compared with noncarriers. In addition, the proportion of subjects with pattern B was significantly larger in the CC group than in the CT/TT group. No association was observed between a functional intronic variation in the fatty acid transport protein-1 (FATP1) gene and LDL-PPD in a cohort of healthy Swedish men (119). However, the cholesterol concentration ratio of the largest and smallest LDL subfractions (LDL-I/LDL-III ratio) was found to be different between FATP1 intron 8 genotypes. No clear association was observed between three SNPs located within the scavenger receptor class B type I (SR-BI) gene and LDL size in the Framingham Study (120). However, this study showed reduced LDL particle size in carriers of the A allele at the SR-BI exon 1 gene in the subgroup of diabetic subjects. Finally, no study investigated the effect of common polymorphisms in the LDLR gene on LDL particle characteristics. However, earlier studies showed that the LDL particles of patients with familial hypercholesterolemia are characterized by higher peak flotation rates and lower density (121, 122). Similarly, one patient with Tangier disease was shown to have smaller particle size compared with control subjects, highlighting the possible implication of the ABCA1 gene (123). However, the reduced LDL size effect of a defective mutation in the ABCA1 gene was not reported in a group of heterozygous subjects (124).

	COMPLEMENTARY GENETIC APPROACHES

TOP ABSTRACT INTRODUCTION GENETIC EPIDEMIOLOGY DNA-BASED VARIANTS COMPLEMENTARY GENETIC APPROACHES CONCLUSION REFERENCES

 
LDL size: a component of the metabolic syndrome and a trait representing a common atherogenic lipoprotein profile
The metabolic syndrome is characterized by a cluster of CAD risk factors, including hypertension, upper body obesity, glucose intolerance, and the atherogenic lipoprotein phenotype, which consists of increased plasma triglyceride levels, low plasma levels of HDL cholesterol (HDL-C), and a predominance of small, dense LDLs (125). The strong association between the small, dense LDL phenotype and the atherogenic lipoprotein profile raises the question of whether the gene proposed by complex segregation analyses is also responsible for the associated lipid and lipoprotein levels. Using factor analysis, Edwards et al. (126, 127) investigated the clustering of risk factors in the Kaiser Permanente Women Twins Study by examining the correlation structure among the components of the metabolic syndrome. Factor analysis reduced 10 correlated risk factors to 3 uncorrelated factors, each reflecting a different aspect of the metabolic syndrome. One of the factors was considered the lipid factor because of the strong factor loading for the lipid variables, including triglyceride, HDL-C, and LDL-PPD. Heritability estimates for the lipid factor were calculated using various approaches and ranged from 0.25 to 0.32. Thus, the authors suggested that approximately one-fourth to one-third of the variance in this composite lipid factor may be attributable to genetic influences. Using a candidate gene strategy, the same research group subsequently found strong evidence of linkage between the lipid factor and the CETP gene (128). The authors proposed that the CETP gene variations influence the covariation in LDL size and triglyceride and HDL-C levels and may account for a portion of the phenotypic correlation between these risk factors.

To investigate the interrelationship between LDL particle size and triglyceride and HDL-C levels, Edwards et al. (52) reported genetic correlations between pairs of traits. The genetic correlation between LDL-PPD and triglyceride was –0.87, suggesting that 76% [_G² = (–0.87)² = 0.76] of the additive genetic variance in LDL size is shared with triglyceride. The genetic correlation between LDL-PPD and HDL-C was more modest (0.65) but suggested that nearly 50% of the additive genetic variance in each of these traits is attributable to shared genes. However, based on the likelihood-ratio test, the hypothesis of complete pleiotropy was rejected for the two genetic correlations, suggesting the existence of unique genes for each trait. These results demonstrated that the observed phenotypic associations between these three traits are largely under genetic control and indicated that searching for genes implicated in LDL size may actually mean searching for genes also involved in triglyceride and HDL-C. A similar study conducted by Rainwater, Martin, and Comuzzie (54) reported a genetic correlation between lipoprotein size traits (LDL and HDL) and triglyceride. Triglyceride and HDL were strongly correlated with LDL, with genetic correlations of –0.76 and 0.56, respectively. Thus, shared genes accounted for 58% and 31% of the genetic variance in each pair of traits.

Small, dense LDL is also metabolically associated with increased plasma apoB levels, and both features are found in patients with FCHL (37). Thus, some investigators searched for a common genetic mechanism between these two traits in families characterized by FCHL. Using bivariate segregation analysis, Juo et al. (129) reported evidence of a common genetic mechanism controlling both apoB levels and the distribution of LDL subfraction (parameter K) in FCHL families. The best-fitting model proposed a common gene with a codominant allele for both traits, plus distinct polygenic components for each trait. This major gene explained 37% and 23% of the variance in parameter K and apoB levels, respectively. On the other hand, Jarvik et al. (130) have shown that LDL subclass phenotype B and apoB levels are two traits influenced by two Mendelian loci independent of each other and modulating the risk of FCHL. This conclusion was drawn by showing 1) that the major gene effect seen in segregation analysis for apoB levels remained after adjustment for LDL subclass phenotypes and 2) that a lack of association between LDL subclass phenotype and the apoB level predicted genotypes in contingency analysis. Finally, using commingling analysis, Austin et al. (131) reported bimodality of apoB levels in individuals with LDL subclass phenotype B. This finding suggested distinct genetic mechanisms for LDL subclass phenotype and apoB levels in FCHL families. The conflicting results between these studies may be attributable to the different statistical strategies used or may simply reflect the complexity of the genetic mechanisms for these traits.

Taken all together, it appears that distinct sets of genes influence LDL size: those that influence LDL size independent of triglyceride and other lipid parameters and those that affect several components of the lipid profile. Thus, in addition to the genes uniquely influencing LDL size, there appear to be genetic factors that are responsible for covariation in lipoprotein/lipid traits, which demonstrates the complexity of characterizing genetic influences on LDL size.

Animal model
Few, but relevant, studies on animal models have confirmed the presence of genetic factors influencing LDL size. First, LDL size varies substantially between different strains of mice, showing the effect of the genetic background. Jiao et al. (132) characterized LDL size by liquid chromatography in 10 inbred strains and observed a LDL size range from 24.16 nm in BALB/c strain to 29.39 nm in SWR strain, with the whole spectrum of sizes within this interval for the other strains. In an attempt to test whether LDL size was an inherited trait in mice, three sets of recombinant inbred strains were produced by crossing strains with different LDL sizes. By this means, authors have shown that the LDL size of recombinant inbred strains segregated to one or another progenitor 88% of the time, implying that LDL size may be controlled by the product of a major gene. Attempts to identify the major LDL size-determining gene yielded only marginal significant results for a RFLP analysis in the APOB gene.

An attempt was also made to establish whether genes control variation in LDL size in baboons (133). A total of 150 baboon members of 19 sire groups were investigated. Baboons were fed three diets contrasting in levels of fat and cholesterol. A multifactor ANOVA revealed that 18.3% of the variation in LDL size was explained by the sire groups. In addition, there was a significant sire-diet interaction on the phenotype, indicating that members of different sire groups responded differently to various dietary compositions. Taken together, these results suggested that genes influence LDL size and the patterns of LDL response to different diets in baboons. Recently, a genome-wide linkage scan was performed among an enlarged group of these baboons to localize the genes that control LDL size fractions (134). Using GGE, four LDL size-related phenotypes were constructed based on fractional absorbance in four intervals of LDL (LDL-4, 24–26 nm; LDL-3, 26–27 nm; LDL-2, 27–28 nm; and LDL-1, 28–30 nm). The LDL median diameter was also estimated, which is the diameter at which half of the LDL absorbance is on larger and half is on smaller particles. Genome scans were performed on LDL size-related phenotypes taken from blood samples collected at the end of each experimental diet. On a high-cholesterol, high-fat diet, significant evidence of linkage (LOD = 4.22) for LDL-2 was observed on the baboon homologs of human chromosomes 20 and 22 (Fig. 1). Two additional QTLs were suggested, one on the baboon homolog of human chromosome 16 for LDL-3 when exposed to a low-cholesterol, low-fat diet (LOD = 2.15) and one on the baboon homolog of human chromosome 5 for LDL-3 when exposed to a low-cholesterol, high-fat diet (LOD = 2.67). The latter QTL is particularly relevant because the signal was also observed for the LDL median diameter (LOD = 2.21). In addition, this locus overlapped with a QTL for LDL-PPD observed in the QFS (Fig. 1), which contains the HMG-CoA reductase gene.

These results have clearly shown the usefulness of animal studies to identify the LDL size genes. Because of our ability to tightly control the animals' environment, these studies might prove to be even more relevant in the future for testing gene-environment interactions.

Gene-gene and gene-environment interactions
Relatively little is known about gene-gene and gene-environment interactions in LDL particle characteristics, but it would be surprising if they were not important. A preliminary study has shown that the LDL bands of MZ twins were more concordant than those of DZ twins before but not after a 22 week exercise program, suggesting that the genetic contribution of LDL subfractions decreases with exercise (135). It was also demonstrated that the LDL size response to a low-fat diet in children was predicted by the parental LDL subclass pattern (136). Tentative evidence of interactions with LDL size phenotypes was also reported for specific loci. A significant interaction was observed between SR-BI exon 1 genotypes and type 2 diabetes on LDL size, indicating that diabetes status modifies the effect of this polymorphism on LDL particle size (120). St-Pierre et al. (104), for example, have shown an inverse effect of the MTP –493G>T genotypes according to visceral adipose tissue and fasting insulin. It is also apparent from association studies (Table 4) that the effects of some loci are sex specific or confined to subgroups of the population (e.g., diabetic). Zambon et al. (137) also reported an interesting pharmacogenetic interaction on LDL density. They showed that the –514C>T polymorphism in the HL gene promoter strongly influences the LDL-Rf response in middle-aged men undergoing intensive lipid-lowering therapy. Although these studies are interesting examples, they demonstrate the high number of interactions that could be tested and the difficulty of doing so in humans. Clearly, when the loci that control small LDLs are mapped, there will be a greater potential for determining the gene-gene and gene-environment interaction effects.

	CONCLUSION

TOP ABSTRACT INTRODUCTION GENETIC EPIDEMIOLOGY DNA-BASED VARIANTS COMPLEMENTARY GENETIC APPROACHES CONCLUSION REFERENCES

 
Here, we synthesized the accumulating evidence of the complex genetic etiology underlying LDL particle heterogeneity. Genetic epidemiology studies have clearly shown a genetic contribution to the LDL subclass phenotypes. Heritability studies have shown that at least 30% to 60% of the variations are attributable to genetic factors. In addition, complex segregation analyses have consistently demonstrated the existence of a single gene with major effect. On the other hand, searching the DNA-based variations responsible has proven to be a difficult task owing to inconsistency and lack of replication among studies. Indeed, linkage and association studies with candidate genes have produced some of the expected results, but in general the effect of positive hits does not seem to be uniform in all populations and environmental backgrounds. Genome-wide linkage scans have been undertaken to fill the gap and have produced interesting leads that need to be followed up.

It is becoming obvious that several different genetic loci contribute to the expression of small, dense LDL. This observation suggests that different genetically determined metabolic mechanisms may give rise to the phenotype. For most of the loci identified to date, it is unclear whether the effect is direct or mediated through the interrelationship with other metabolic parameters, such as glucose/insulin homeostasis and triglyceride metabolism. The false positives reported are difficult to assess but may be important as a result of publication bias toward positive findings. Accordingly, this summary should be interpreted with caution and awareness because some of the positive loci may eventually prove to be false positives.

Understanding the genetic cause of small, dense LDL will help us elucidate the complex multifactorial network involved in the progression of atherosclerosis and its ultimate consequence, CHD. Although searching the genes has been and continues to be a demanding undertaking, the challenge may still be ahead to identify the combination of genes and environmental circumstances that predispose to small, dense LDL. It should be emphasized, however, that the nongenetic factors influencing the expression of small, dense LDL can be used to our advantage by treating genetically susceptible individuals with appropriate lifestyle modifications.

View larger version (45K): [in this window] [in a new window]   Fig. 1. continued ideogram was obtained from the University of California, Santa Cruz Genome Browser (http://genome.ucsc.edu). The alternating black and white colors on the chromosomes have been used to distinguish a cytogenic band from the adjacent ones and do not correspond to the band colors observed on Giemsa-stained chromosomes. ADRB3, ß3-adrenergic receptor; APOB, apolipoprotein B; Chr, chromosome; CETP, cholesteryl ester transfer protein; CYBA, p22 phox; LDLR, low density lipoprotein receptor; LIPC, hepatic lipase; MTP, microsomal triglyceride transfer protein; SOD2, manganese superoxide dismutase; SRB1, scavenger receptor class B type I.

	ACKNOWLEDGMENTS

Manuscript received January 20, 2004 and in revised form March 15, 2004.

	REFERENCES

TOP ABSTRACT INTRODUCTION GENETIC EPIDEMIOLOGY DNA-BASED VARIANTS COMPLEMENTARY GENETIC APPROACHES CONCLUSION REFERENCES

1. 2001. Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (Adult Treatment Panel III). J. Am. Med. Assoc. 285: 2486–2497.

2. Shen, M. M., R. M. Krauss, F. T. Lindgren, and T. M. Forte. 1981. Heterogeneity of serum low density lipoproteins in normal human subjects. J. Lipid Res. 22: 236–244.[Abstract]

3. Krauss, R. M., and D. J. Burke. 1982. Identification of multiple subclasses of plasma low density lipoproteins in normal humans. J. Lipid Res. 23: 97–104.[Abstract]

4. Ghosh, S., M. K. Basu, and J. S. Schweppe. 1973. Charge heterogeneity of human low density lipoprotein (LDL). Proc. Soc. Exp. Biol. Med. 142: 1322–1325.[CrossRef][Medline]

5. Austin, M. A., J. E. Hokanson, and J. D. Brunzell. 1994. Characterization of low-density lipoprotein subclasses: methodologic approaches and clinical relevance. Curr. Opin. Lipidol. 5: 395–403.[Medline]

6. Gardner, C. D., S. P. Fortmann, and R. M. Krauss. 1996. Association of small low-density lipoprotein particles with the incidence of coronary artery disease in men and women. J. Am. Med. Assoc. 276: 875–881.[Abstract/Free Full Text]

7. Stampfer, M. J., R. M. Krauss, J. Ma, P. J. Blanche, L. G. Holl, F. M. Sacks, and C. H. Hennekens. 1996. A prospective study of triglyceride level, low-density lipoprotein particle diameter, and risk of myocardial infarction. J. Am. Med. Assoc. 276: 882–888.[Abstract/Free Full Text]

8. Lamarche, B., A. Tchernof, S. Moorjani, B. Cantin, G. R. Dagenais, P. J. Lupien, and J. P. Despres. 1997. Small, dense low-density lipoprotein particles as a predictor of the risk of ischemic heart disease in men. Prospective results from the Quebec Cardiovascular Study. Circulation. 95: 69–75.[Abstract/Free Full Text]

9. Lamarche, B., A. C. St-Pierre, I. L. Ruel, B. Cantin, G. R. Dagenais, and J. P. Despres. 2001. A prospective, population-based study of low density lipoprotein particle size as a risk factor for ischemic heart disease in men. Can. J. Cardiol. 17: 859–865.[Medline]

10. Chait, A., R. L. Brazg, D. L. Tribble, and R. M. Krauss. 1993. Susceptibility of small, dense, low-density lipoproteins to oxidative modification in subjects with the atherogenic lipoprotein phenotype, pattern B. Am. J. Med. 94: 350–356.[CrossRef][Medline]

11. de Graaf, J., H. L. Hak-Lemmers, M. P. Hectors, P. N. Demacker, J. C. Hendriks, and A. F. Stalenhoef. 1991. Enhanced susceptibility to in vitro oxidation of the dense low density lipoprotein subfraction in healthy subjects. Arterioscler. Thromb. 11: 298–306.[Abstract/Free Full Text]

12. de Graaf, J., J. C. Hendriks, P. N. Demacker, and A. F. Stalenhoef. 1993. Identification of multiple dense LDL subfractions with enhanced susceptibility to in vitro oxidation among hypertriglyceridemic subjects. Normalization after clofibrate treatment. Arterioscler. Thromb. 13: 712–719.[Abstract/Free Full Text]

13. Dejager, S., E. Bruckert, and M. J. Chapman. 1993. Dense low density lipoprotein subspecies with diminished oxidative resistance predominate in combined hyperlipidemia. J. Lipid Res. 34: 295–308.[Abstract]

14. Tribble, D. L., L. G. Holl, P. D. Wood, and R. M. Krauss. 1992. Variations in oxidative susceptibility among six low density lipoprotein subfractions of differing density and particle size. Atherosclerosis. 93: 189–199.[CrossRef][Medline]

15. Campos, H., K. S. Arnold, M. E. Balestra, T. L. Innerarity, and R. M. Krauss. 1996. Differences in receptor binding of LDL subfractions. Arterioscler. Thromb. Vasc. Biol. 16: 794–801.[Abstract/Free Full Text]

16. Chen, G. C., W. Liu, P. Duchateau, J. Allaart, R. L. Hamilton, C. M. Mendel, K. Lau, D. A. Hardman, P. H. Frost, M. J. Malloy, and J. P. Kane. 1994. Conformational differences in human apolipoprotein B-100 among subspecies of low density lipoproteins (LDL). Association of altered proteolytic accessibility with decreased receptor binding of LDL subspecies from hypertriglyceridemic subjects. J. Biol. Chem. 269: 29121–29128.[Abstract/Free Full Text]

17. Galeano, N. F., R. Milne, Y. L. Marcel, M. T. Walsh, E. Levy, T. D. Ngu'yen, A. Gleeson, Y. Arad, L. Witte, M. Al-Haideri, S. C. Rumsey, and R. J. Deckelbaum. 1994. Apoprotein B structure and receptor recognition of triglyceride-rich low density lipoprotein (LDL) is modified in small LDL but not in triglyceride-rich LDL of normal size. J. Biol. Chem. 269: 511–519.[Abstract/Free Full Text]

18. Nigon, F., P. Lesnik, M. Rouis, and M. J. Chapman. 1991. Discrete subspecies of human low density lipoproteins are heterogeneous in their interaction with the cellular LDL receptor. J. Lipid Res. 32: 1741–1753.[Abstract]

19. Teng, B., A. Sniderman, R. M. Krauss, P. O. Kwiterovich, Jr., R. W. Milne, and Y. L. Marcel. 1985. Modulation of apolipoprotein B antigenic determinants in human low density lipoprotein subclasses. J. Biol. Chem. 260: 5067–5072.[Abstract/Free Full Text]

20. Anber, V., B. A. Griffin, M. McConnell, C. J. Packard, and J. Shepherd. 1996. Influence of plasma lipid and LDL-subfraction profile on the interaction between low density lipoprotein with human arterial wall proteoglycans. Atherosclerosis. 124: 261–271.[CrossRef][Medline]

21. Anber, V., J. S. Millar, M. McConnell, J. Shepherd, and C. J. Packard. 1997. Interaction of very-low-density, intermediate-density, and low-density lipoproteins with human arterial wall proteoglycans. Arterioscler. Thromb. Vasc. Biol. 17: 2507–2514.[Abstract/Free Full Text]

22. Camejo, G., B. Rosengren, U. Olson, F. Lopez, S. O. Olofson, C. Westerlund, and G. Bondjers. 1990. Molecular basis of the association of arterial proteoglycans with low density lipoproteins: its effect on the structure of the lipoprotein particle. Eur. Heart J. 11 (Suppl. E): 164–173.

23. Galeano, N. F., M. Al-Haideri, F. Keyserman, S. C. Rumsey, and R. J. Deckelbaum. 1998. Small dense low density lipoprotein has increased affinity for LDL receptor-independent cell surface binding sites: a potential mechanism for increased atherogenicity. J. Lipid Res. 39: 1263–1273.[Abstract/Free Full Text]

24. Bjornheden, T., A. Babyi, G. Bondjers, and O. Wiklund. 1996. Accumulation of lipoprotein fractions and subfractions in the arterial wall, determined in an in vitro perfusion system. Atherosclerosis. 123: 43–56.[CrossRef][Medline]

25. Nielsen, L. B. 1996. Transfer of low density lipoprotein into the arterial wall and risk of atherosclerosis. Atherosclerosis. 123: 1–15.[CrossRef][Medline]

26. Vakkilainen, J., S. Makimattila, A. Seppala-Lindroos, S. Vehkavaara, S. Lahdenpera, P. H. Groop, M. R. Taskinen, and H. Yki-Jarvinen. 2000. Endothelial dysfunction in men with small LDL particles. Circulation. 102: 716–721.[Abstract/Free Full Text]

27. Veniant, M. M., S. Withycombe, and S. G. Young. 2001. Lipoprotein size and atherosclerosis susceptibility in Apoe(–/–) and Ldlr(–/–) mice. Arterioscler. Thromb. Vasc. Biol. 21: 1567–1570.[Abstract/Free Full Text]

28. Miller, B. D., E. L. Alderman, W. L. Haskell, J. M. Fair, and R. M. Krauss. 1996. Predominance of dense low-density lipoprotein particles predicts angiographic benefit of therapy in the Stanford Coronary Risk Intervention Project. Circulation. 94: 2146–2153.[Abstract/Free Full Text]

29. Zambon, A., J. E. Hokanson, B. G. Brown, and J. D. Brunzell. 1999. Evidence for a new pathophysiological mechanism for coronary artery disease regression: hepatic lipase-mediated changes in LDL density. Circulation. 99: 1959–1964.[Abstract/Free Full Text]

30. Campos, H., L. A. Moye, S. P. Glasser, M. J. Stampfer, and F. M. Sacks. 2001. Low-density lipoprotein size, pravastatin treatment, and coronary events. J. Am. Med. Assoc. 286: 1468–1474.[Abstract/Free Full Text]

31. Campos, H., G. O. Roederer, S. Lussier-Cacan, J. Davignon, and R. M. Krauss. 1995. Predominance of large LDL and reduced HDL2 cholesterol in normolipidemic men with coronary artery disease. Arterioscler. Thromb. Vasc. Biol. 15: 1043–1048.[Abstract/Free Full Text]

32. Gray, R. S., D. C. Robbins, W. Wang, J. L. Yeh, R. R. Fabsitz, L. D. Cowan, T. K. Welty, E. T. Lee, R. M. Krauss, and B. V. Howard. 1997. Relation of LDL size to the insulin resistance syndrome and coronary heart disease in American Indians. The Strong Heart Study. Arterioscler. Thromb. Vasc. Biol. 17: 2713–2720.[Abstract/Free Full Text]

33. Ruotolo, G., C. Tettamanti, M. P. Garancini, F. Ragogna, G. Derosa, L. Nardecchia, F. Parlato, and G. Pozza. 1998. Smaller, denser LDL particles are not a risk factor for cardiovascular disease in healthy nonagenarian women of the Cremona Population Study. Atherosclerosis. 140: 65–70.[CrossRef][Medline]

34. Wahi, S., C. D. Gatzka, B. Sherrard, H. Simpson, V. Collins, G. Dowse, P. Zimmet, G. Jennings, and A. M. Dart. 1997. Risk factors for coronary heart disease in a population with a high prevalence of obesity and diabetes: a case-control study of the Polynesian population of Western Samoa. J. Cardiovasc. Risk. 4: 173–178.[CrossRef][Medline]

35. Mykkanen, L., J. Kuusisto, S. M. Haffner, M. Laakso, and M. A. Austin. 1999. LDL size and risk of coronary heart disease in elderly men and women. Arterioscler. Thromb. Vasc. Biol. 19: 2742–2748.[Abstract/Free Full Text]

36. Krauss, R. M. 2002. Is the size of low-density lipoprotein particles related to the risk of coronary heart disease? J. Am. Med. Assoc. 287: 712–713.[Free Full Text]

37. Kwiterovich, P. O., Jr. 2002. Clinical relevance of the biochemical, metabolic, and genetic factors that influence low-density lipoprotein heterogeneity. Am. J. Cardiol. 90: 30i–47i.[Medline]

38. Lindgren, F. T., L. C. Jensen, R. D. Wills, and N. K. Freeman. 1969. Flotation rates, molecular weights and hydrated densities of the low-density lipoproteins. Lipids. 4: 337–344.[CrossRef][Medline]

39. Austin, M. A., J. L. Breslow, C. H. Hennekens, J. E. Buring, W. C. Willett, and R. M. Krauss. 1988. Low-density lipoprotein subclass patterns and risk of myocardial infarction. J. Am. Med. Assoc. 260: 1917–1921.[Abstract/Free Full Text]

40. Tchernof, A., B. Lamarche, D. Prud'Homme, A. Nadeau, S. Moorjani, F. Labrie, P. J. Lupien, and J. P. Despres. 1996. The dense LDL phenotype. Association with plasma lipoprotein levels, visceral obesity, and hyperinsulinemia in men. Diabetes Care. 19: 629–637.[Abstract]

41. Campos, H., J. J. Genest, E. Blijlevens, J. R. McNamara, J. L. Jenner, J. M. Ordovas, P. W. Wilson, and E. J. Schaefer. 1992. Low density lipoprotein particle size and coronary artery disease. Arterioscler. Thromb. 12: 187–195.[Abstract/Free Full Text]

42. Krauss, R. M., and P. J. Blanche. 1992. Detection and quantitation of LDL subfractions. Curr. Opin. Lipidol. 3: 377–383.[CrossRef]

43. Otvos, J. D. 2002. Measurement of lipoprotein subclass profiles by nuclear magnetic resonance spectroscopy. Clin. Lab. 48: 171–180.[Medline]

44. Fisher, W. R., M. G. Hammond, M. C. Mengel, and G. L. Warmke. 1975. A genetic determinant of the phenotypic variance of the molecular weight of low density lipoprotein. Proc. Natl. Acad. Sci. USA. 72: 2347–2351.[Abstract/Free Full Text]

45. Haffner, S. M., R. D'Agostino, Jr., D. Goff, B. Howard, A. Festa, M. F. Saad, and L. Mykkanen. 1999. LDL size in African Americans, Hispanics, and non-Hispanic whites: the insulin resistance atherosclerosis study. Arterioscler. Thromb. Vasc. Biol. 19: 2234–2240.[Abstract/Free Full Text]

46. Haffner, S. M., L. Mykkanen, R. A. Valdez, M. Paidi, M. P. Stern, and B. V. Howard. 1993. LDL size and subclass pattern in a biethnic population. Arterioscler. Thromb. 13: 1623–1630.[Abstract/Free Full Text]

47. Bossé, Y., M. C. Vohl, J. P. Despres, B. Lamarche, T. Rice, D. C. Rao, C. Bouchard, and L. Perusse. 2003. Heritability of LDL peak particle diameter in the Quebec Family Study. Genet. Epidemiol. 25: 375–381.[CrossRef][Medline]

48. Vakkilainen, J., P. Pajukanta, R. M. Cantor, I. O. Nuotio, S. Lahdenpera, K. Ylitalo, J. Pihlajamaki, P. T. Kovanen, M. Laakso, J. S. Viikari, L. Peltonen, and M. R. Taskinen. 2002. Genetic influences contributing to LDL particle size in familial combined hyperlipidaemia. Eur. J. Hum. Genet. 10: 547–552.[CrossRef][Medline]

49. Lamon-Fava, S., D. Jimenez, J. C. Christian, R. R. Fabsitz, T. Reed, D. Carmelli, W. P. Castelli, J. M. Ordovas, P. W. Wilson, and E. J. Schaefer. 1991. The NHLBI Twin Study: heritability of apolipoprotein A-I, B, and low density lipoprotein subclasses and concordance for lipoprotein(a). Atherosclerosis. 91: 97–106.[CrossRef][Medline]

50. Christian, J. C., K. W. Kang, and J. J. Norton, Jr. 1974. Choice of an estimate of genetic variance from twin data. Am. J. Hum. Genet. 26: 154–161.[Medline]

51. Austin, M. A., B. Newman, J. V. Selby, K. Edwards, E. J. Mayer, and R. M. Krauss. 1993. Genetics of LDL subclass phenotypes in women twins. Concordance, heritability, and commingling analysis. Arterioscler. Thromb. 13: 687–695.[Abstract/Free Full Text]

52. Edwards, K. L., M. C. Mahaney, A. G. Motulsky, and M. A. Austin. 1999. Pleiotropic genetic effects on LDL size, plasma triglyceride, and HDL cholesterol in families. Arterioscler. Thromb. Vasc. Biol. 19: 2456–2464.[Abstract/Free Full Text]

53. Barzilai, N., G. Atzmon, C. Schechter, E. J. Schaefer, A. L. Cupples, R. Lipton, S. Cheng, and A. R. Shuldiner. 2003. Unique lipoprotein phenotype and genotype associated with exceptional longevity. J. Am. Med. Assoc. 290: 2030–2040.[Abstract/Free Full Text]

54. Rainwater, D. L., L. J. Martin, and A. G. Comuzzie. 2001. Genetic control of coordinated changes in HDL and LDL size phenotypes. Arterioscler. Thromb. Vasc. Biol. 21: 1829–1833.[Abstract/Free Full Text]

55. Krauss, R. M. 2001. Dietary and genetic effects on low-density lipoprotein heterogeneity. Annu. Rev. Nutr. 21: 283–295.[CrossRef][Medline]

56. Kraus, W. E., J. A. Houmard, B. D. Duscha, K. J. Knetzger, M. B. Wharton, J. S. McCartney, C. W. Bales, S. Henes, G. P. Samsa, J. D. Otvos, K. R. Kulkarni, and C. A. Slentz. 2002. Effects of the amount and intensity of exercise on plasma lipoproteins. N. Engl. J. Med. 347: 1483–1492.[Abstract/Free Full Text]

57. Terry, R. B., P. D. Wood, W. L. Haskell, M. L. Stefanick, and R. M. Krauss. 1989. Regional adiposity patterns in relation to lipids, lipoprotein cholesterol, and lipoprotein subfraction mass in men. J. Clin. Endocrinol. Metab. 68: 191–199.[Abstract/Free Full Text]

58. Reaven, G. M., Y. D. Chen, J. Jeppesen, P. Maheux, and R. M. Krauss. 1993. Insulin resistance and hyperinsulinemia in individuals with small, dense low density lipoprotein particles. J. Clin. Invest. 92: 141–146.

59. Austin, M. A. 1994. Genetic and environmental influences on LDL subclass phenotypes. Clin. Genet. 46: 64–70.[Medline]

60. Maclean, C. J., N. E. Morton, R. C. Elston, and S. Yee. 1976. Skewness in commingled distributions. Biometrics. 32: 695–699.[CrossRef][Medline]

61. Austin, M. A., G. P. Jarvik, J. E. Hokanson, and K. Edwards. 1993. Complex segregation analysis of LDL peak particle diameter. Genet. Epidemiol. 10: 599–604.[CrossRef][Medline]

62. Friedlander, Y., J. D. Kark, R. Sinnreich, K. L. Edwards, and M. A. Austin. 1999. Inheritance of LDL peak particle diameter: results from a segregation analysis in Israeli families. Genet. Epidemiol. 16: 382–396.[CrossRef][Medline]

63. Austin, M. A., and R. M. Krauss. 1986. Genetic control of low-density-lipoprotein subclasses. Lancet. 2: 592–595.[Medline]

64. Austin, M. A., M. C. King, K. M. Vranizan, B. Newman, and R. M. Krauss. 1988. Inheritance of low-density lipoprotein subclass patterns: results of complex segregation analysis. Am. J. Hum. Genet. 43: 838–846.[Medline]

65. Austin, M. A., J. D. Brunzell, W. L. Fitch, and R. M. Krauss. 1990. Inheritance of low density lipoprotein subclass patterns in familial combined hyperlipidemia. Arteriosclerosis. 10: 520–530.[Abstract/Free Full Text]

66. de Graaf, J., D. W. Swinkels, A. F. de Haan, P. N. Demacker, and A. F. Stalenhoef. 1992. Both inherited susceptibility and environmental exposure determine the low-density lipoprotein-subfraction pattern distribution in healthy Dutch families. Am. J. Hum. Genet. 51: 1295–1310.[Medline]

67. Duggirala, R., J. T. Williams, S. Williams-Blangero, and J. Blangero. 1997. A variance component approach to dichotomous trait linkage analysis using a threshold model. Genet. Epidemiol. 14: 987–992.[CrossRef][Medline]

68. Bredie, S. J., L. A. Kiemeney, A. F. de Haan, P. N. Demacker, and A. F. Stalenhoef. 1996. Inherited susceptibility determines the distribution of dense low-density lipoprotein subfraction profiles in familial combined hyperlipidemia. Am. J. Hum. Genet. 58: 812–822.[Medline]

69. Austin, M. A., E. Wijsman, S. W. Guo, R. M. Krauss, J. D. Brunzell, and S. Deeb. 1991. Lack of evidence for linkage between low-density lipoprotein subclass phenotypes and the apolipoprotein B locus in familial combined hyperlipidemia. Genet. Epidemiol. 8: 287–297.[CrossRef][Medline]

70. LaBelle, M., M. A. Austin, E. Rubin, and R. M. Krauss. 1991. Linkage analysis of low-density lipoprotein subclass phenotypes and the apolipoprotein B gene. Genet. Epidemiol. 8: 269–275.[CrossRef][Medline]

71. Rotter, J. I., X. Bu, R. M. Cantor, C. H. Warden, J. Brown, R. J. Gray, P. J. Blanche, R. M. Krauss, and A. J. Lusis. 1996. Multilocus genetic determinants of LDL particle size in coronary artery disease families. Am. J. Hum. Genet. 58: 585–594.[Medline]

72. Austin, M. A., P. J. Talmud, L. A. Luong, L. Haddad, I. N. Day, B. Newman, K. L. Edwards, R. M. Krauss, and S. E. Humphries. 1998. Candidate-gene studies of the atherogenic lipoprotein phenotype: a sib-pair linkage analysis of DZ women twins. Am. J. Hum. Genet. 62: 406–419.[CrossRef][Medline]

73. Nishina, P. M., J. P. Johnson, J. K. Naggert, and R. M. Krauss. 1992. Linkage of atherogenic lipoprotein phenotype to the low density lipoprotein receptor locus on the short arm of chromosome 19. Proc. Natl. Acad. Sci. USA. 89: 708–712.[Abstract/Free Full Text]

74. Allayee, H., B. E. Aouizerat, R. M. Cantor, G. M. Dallinga-Thie, R. M. Krauss, C. D. Lanning, J. I. Rotter, A. J. Lusis, and T. W. de Bruin. 1998. Families with familial combined hyperlipidemia and families enriched for coronary artery disease share genetic determinants for the atherogenic lipoprotein phenotype. Am. J. Hum. Genet. 63: 577–585.[CrossRef][Medline]

75. Austin, M. A., K. Stephens, C. E. Walden, and E. Wijsman. 1999. Linkage analysis of candidate genes and the small, dense low-density lipoprotein phenotype. Atherosclerosis. 142: 79–87.[CrossRef][Medline]

76. Naggert, J. K., A. Recinos, J. E. Lamerdin, R. M. Krauss, and P. M. Nishina. 1997. The atherogenic lipoprotein phenotype is not caused by a mutation in the coding region of the low density lipoprotein receptor gene. Clin. Genet. 51: 236–240.[Medline]

77. Hokanson, J. E., J. D. Brunzell, G. P. Jarvik, E. M. Wijsman, and M. A. Austin. 1999. Linkage of low-density lipoprotein size to the lipoprotein lipase gene in heterozygous lipoprotein lipase deficiency. Am. J. Hum. Genet. 64: 608–618.[CrossRef][Medline]

78. Allayee, H., K. M. Dominguez, B. E. Aouizerat, R. M. Krauss, J. I. Rotter, J. Lu, R. M. Cantor, T. W. de Bruin, and A. J. Lusis. 2000. Contribution of the hepatic lipase gene to the atherogenic lipoprotein phenotype in familial combined hyperlipidemia. J. Lipid Res. 41: 245–252.[Abstract/Free Full Text]

79. Talmud, P. J., K. L. Edwards, C. M. Turner, B. Newman, J. M. Palmen, S. E. Humphries, and M. A. Austin. 2000. Linkage of the cholesteryl ester transfer protein (CETP) gene to LDL particle size: use of a novel tetranucleotide repeat within the CETP promoter. Circulation. 101: 2461–2466.[Abstract/Free Full Text]

80. Bosse, Y., L. Perusse, J. P. Despres, B. Lamarche, Y. C. Chagnon, T. Rice, D. C. Rao, C. Bouchard, and M. C. Vohl. 2003. Evidence for a major quantitative trait locus on chromosome 17q21 affecting low-density lipoprotein peak particle diameter. Circulation. 107: 2361–2368.[Abstract/Free Full Text]

81. Austin, M. A., K. L. Edwards, S. A. Monks, K. M. Koprowicz, J. D. Brunzell, A. G. Motulsky, M. C. Mahaney, and J. E. Hixson. 2003. Genome-wide scan for quantitative trait loci influencing LDL size and plasma triglyceride in familial hypertriglyceridemia. J. Lipid Res. 44: 2161–2168.[Abstract/Free Full Text]

82. Rainwater, D. L., L. Almasy, J. Blangero, S. A. Cole, J. L. VandeBerg, J. W. MacCluer, and J. E. Hixson. 1999. A genome search identifies major quantitative trait loci on human chromosomes 3 and 4 that influence cholesterol concentrations in small LDL particles. Arterioscler. Thromb. Vasc. Biol. 19: 777–783.[Abstract/Free Full Text]

83. Schaefer, E. J., S. Lamon-Fava, S. Johnson, J. M. Ordovas, M. M. Schaefer, W. P. Castelli, and P. W. Wilson. 1994. Effects of gender and menopausal status on the association of apolipoprotein E phenotype with plasma lipoprotein levels. Results from the Framingham Offspring Study. Arterioscler. Thromb. 14: 1105–1113.[Abstract/Free Full Text]

84. Okumura, K., H. Matsui, K. Kawakami, Y. Numaguchi, S. Kaneko, I. Morishima, S. Mokuno, Y. Toki, and T. Hayakawa. 1999. Relationship between the apolipoprotein E and angiotensin-converting enzyme genotypes and LDL particle size in Japanese subjects. Clin. Chim. Acta. 285: 91–103.[CrossRef][Medline]

85. Skoglund-Andersson, C., E. Ehrenborg, R. M. Fisher, G. Olivecrona, A. Hamsten, and F. Karpe. 2003. Influence of common variants in the CETP, LPL, HL and APO E genes on LDL heterogeneity in healthy, middle-aged men. Atherosclerosis. 167: 311–317.[CrossRef][Medline]

86. Haffner, S. M., M. P. Stern, H. Miettinen, D. Robbins, and B. V. Howard. 1996. Apolipoprotein E polymorphism and LDL size in a biethnic population. Arterioscler. Thromb. Vasc. Biol. 16: 1184–1188.[Abstract/Free Full Text]

87. Nikkilä, M., T. Pitkajarvi, T. Koivula, T. Solakivi, T. Lehtimaki, P. Laippala, H. Jokela, E. Lehtomaki, K. Seppa, and P. Sillanaukee. 1996. Women have a larger and less atherogenic low density lipoprotein particle size than men. Atherosclerosis. 119: 181–190.[CrossRef][Medline]

88. Zhao, S. P., M. H. Verhoeven, J. Vink, L. Hollaar, A. van der Laarse, P. de Knijff, and F. M. van 't Hooft. 1993. Relationship between apolipoprotein E and low density lipoprotein particle size. Atherosclerosis. 102: 147–154.[CrossRef][Medline]

89. Isasi, C. R., S. Shea, R. J. Deckelbaum, S. C. Couch, T. J. Starc, J. D. Otvos, and L. Berglund. 2000. Apolipoprotein epsilon2 allele is associated with an anti-atherogenic lipoprotein profile in children: The Columbia University BioMarkers Study. Pediatrics. 106: 568–575.[Abstract/Free Full Text]

90. Barbagallo, C. M., F. Polizzi, M. Severino, M. Rizzo, N. Vivona, F. Onorato, R. Caldarella, A. B. Cefalu, D. Noto, A. Notarbartolo, and M. R. Averna. 2001. ApoE polymorphism in a small Mediterranean island: relationships with plasma lipids, lipoproteins and LDL particle size. Eur. J. Epidemiol. 17: 707–713.[CrossRef][Medline]

91. Dart, A. M., and B. Cooper. 1999. Independent effects of Apo E phenotype and plasma triglyceride on lipoprotein particle sizes in the fasting and postprandial states. Arterioscler. Thromb. Vasc. Biol. 19: 2465–2473.[Abstract/Free Full Text]

92. Vega, G. L., L. T. Clark, A. Tang, S. Marcovina, S. M. Grundy, and J. C. Cohen. 1998. Hepatic lipase activity is lower in African American men than in white American men: effects of 5' flanking polymorphism in the hepatic lipase gene (LIPC). J. Lipid Res. 39: 228–232.[Abstract/Free Full Text]

93. Zambon, A., S. S. Deeb, J. E. Hokanson, B. G. Brown, and J. D. Brunzell. 1998. Common variants in the promoter of the hepatic lipase gene are associated with lower levels of hepatic lipase activity, buoyant LDL, and higher HDL2 cholesterol. Arterioscler. Thromb. Vasc. Biol. 18: 1723–1729.[Abstract/Free Full Text]

94. Carr, M. C., A. F. Ayyobi, S. J. Murdoch, S. S. Deeb, and J. D. Brunzell. 2002. Contribution of hepatic lipase, lipoprotein lipase, and cholesteryl ester transfer protein to LDL and HDL heterogeneity in healthy women. Arterioscler. Thromb. Vasc. Biol. 22: 667–673.[Abstract/Free Full Text]

95. Couture, P., J. D. Otvos, L. A. Cupples, C. Lahoz, P. W. Wilson, E. J. Schaefer, and J. M. Ordovas. 2000. Association of the C-514T polymorphism in the hepatic lipase gene with variations in lipoprotein subclass profiles: The Framingham Offspring Study. Arterioscler. Thromb. Vasc. Biol. 20: 815–822.[Abstract/Free Full Text]

96. Humphries, S. E., L. Berglund, C. R. Isasi, J. D. Otvos, D. Kaluski, R. J. Deckelbaum, S. Shea, and P. J. Talmud. 2002. Loci for CETP, LPL, LIPC, and APOC3 affect plasma lipoprotein size and sub-population distribution in Hispanic and non-Hispanic white subjects: the Columbia University BioMarkers Study. Nutr. Metab. Cardiovasc. Dis. 12: 163–172.[Medline]

97. Sakai, N., Y. Matsuzawa, K. Hirano, S. Yamashita, S. Nozaki, Y. Ueyama, M. Kubo, and S. Tarui. 1991. Detection of two species of low density lipoprotein particles in cholesteryl ester transfer protein deficiency. Arterioscler. Thromb. 11: 71–79.[Abstract/Free Full Text]

98. Ordovas, J. M., L. A. Cupples, D. Corella, J. D. Otvos, D. Osgood, A. Martinez, C. Lahoz, O. Coltell, P. W. Wilson, and E. J. Schaefer. 2000. Association of cholesteryl ester transfer protein-TaqIB polymorphism with variations in lipoprotein subclasses and coronary heart disease risk: the Framingham Study. Arterioscler. Thromb. Vasc. Biol. 20: 1323–1329.[Abstract/Free Full Text]

99. Brousseau, M. E., J. J. O'Connor, Jr., J. M. Ordovas, D. Collins, J. D. Otvos, T. Massov, J. R. McNamara, H. B. Rubins, S. J. Robins, and E. J. Schaefer. 2002. Cholesteryl ester transfer protein TaqI B2B2 genotype is associated with higher HDL cholesterol levels and lower risk of coronary heart disease end points in men with HDL deficiency: Veterans Affairs HDL Cholesterol Intervention Trial. Arterioscler. Thromb. Vasc. Biol. 22: 1148–1154.[Abstract/Free Full Text]

100. Bernard, S., P. Moulin, L. Lagrost, S. Picard, M. Elchebly, G. Ponsin, F. Chapuis, and F. Berthezene. 1998. Association between plasma HDL-cholesterol concentration and Taq1B CETP gene polymorphism in non-insulin-dependent diabetes mellitus. J. Lipid Res. 39: 59–65.[Abstract/Free Full Text]

101. Okumura, K., H. Matsui, H. Kamiya, Y. Saburi, K. Hayashi, and T. Hayakawa. 2002. Differential effect of two common polymorphisms in the cholesteryl ester transfer protein gene on low-density lipoprotein particle size. Atherosclerosis. 161: 425–431.[CrossRef][Medline]

102. Wang, J., H. Qiang, D. Chen, C. Zhang, and Y. Zhuang. 2002. CETP gene mutation (D442G) increases low-density lipoprotein particle size in patients with coronary heart disease. Clin. Chim. Acta. 322: 85–90.[CrossRef][Medline]

103. Couture, P., J. D. Otvos, L. A. Cupples, P. W. Wilson, E. J. Schaefer, and J. M. Ordovas. 2000. Absence of association between genetic variation in the promoter of the microsomal triglyceride transfer protein gene and plasma lipoproteins in the Framingham Offspring Study. Atherosclerosis. 148: 337–343.[CrossRef][Medline]

104. St-Pierre, J., I. Lemieux, I. Miller-Felix, D. Prud'homme, J. Bergeron, D. Gaudet, A. Nadeau, J. P. Despres, and M. C. Vohl. 2002. Visceral obesity and hyperinsulinemia modulate the impact of the microsomal triglyceride transfer protein –493G/T polymorphism on plasma lipoprotein levels in men. Atherosclerosis. 160: 317–324.[CrossRef][Medline]

105. Chen, L., G. Yoshino, E. Maeda, and S. Zeng. 2003. Effect of microsomal triglyceride transfer protein gene polymorphism in the promoter region on dyslipidemia in type 2 diabetic subjects. Chin. Med. J. (Engl.). 116: 215–217.

106. Miesenböck, G., B. Holzl, B. Foger, E. Brandstatter, B. Paulweber, F. Sandhofer, and J. R. Patsch. 1993. Heterozygous lipoprotein lipase deficiency due to a missense mutation as the cause of impaired triglyceride tolerance with multiple lipoprotein abnormalities. J. Clin. Invest. 91: 448–455.

107. Bertolini, S., M. L. Simone, G. M. Pes, M. Ghisellini, M. Rolleri, A. Bellocchio, N. Elicio, P. Masturzo, and S. Calandra. 2000. Pseudodominance of lipoprotein lipase (LPL) deficiency due to a nonsense mutation (Tyr302>Term) in exon 6 of LPL gene in an Italian family from Sardinia (LPL(Olbia)). Clin. Genet. 57: 140–147.[CrossRef][Medline]

108. Sawano, M., Y. Watanabe, H. Ohmura, K. Shimada, H. Daida, H. Mokuno, and H. Yamaguchi. 2001. Potentially protective effects of the Ser447-Ter mutation of the lipoprotein lipase gene against the development of coronary artery disease in Japanese subjects via a beneficial lipid profile. Jpn. Circ. J. 65: 310–314.[CrossRef][Medline]

109. Kozaki, K., T. Gotoda, M. Kawamura, H. Shimano, Y. Yazaki, Y. Ouchi, H. Orimo, and N. Yamada. 1993. Mutational analysis of human lipoprotein lipase by carboxy-terminal truncation. J. Lipid Res. 34: 1765–1772.[Abstract]

110. Ruel, I. L., D. Gaudet, P. Perron, J. Bergeron, P. Julien, and B. Lamarche. 2002. Characterization of LDL particle size among carriers of a defective or a null mutation in the lipoprotein lipase gene: the Quebec LIPD Study. Arterioscler. Thromb. Vasc. Biol. 22: 1181–1186.[Abstract/Free Full Text]

111. Russo, G. T., J. B. Meigs, L. A. Cupples, S. Demissie, J. D. Otvos, P. W. Wilson, C. Lahoz, D. Cucinotta, P. Couture, T. Mallory, E. J. Schaefer, and J. M. Ordovas. 2001. Association of the Sst-I polymorphism at the APOC3 gene locus with variations in lipid levels, lipoprotein subclass profiles and coronary heart disease risk: the Framingham Offspring Study. Atherosclerosis. 158: 173–181.[CrossRef][Medline]

112. Brown, S., J. M. Ordovas, and H. Campos. 2003. Interaction between the APOC3 gene promoter polymorphisms, saturated fat intake and plasma lipoproteins. Atherosclerosis. 170: 307–313.[CrossRef][Medline]

113. Védie, B., X. Jeunemaitre, J. L. Megnien, I. Myara, H. Trebeden, A. Simon, and N. Moatti. 1998. Charge heterogeneity of LDL in asymptomatic hypercholesterolemic men is related to lipid parameters and variations in the ApoB and CIII genes. Arterioscler. Thromb. Vasc. Biol. 18: 1780–1789.[Abstract/Free Full Text]

114. Austin, M. A., P. J. Talmud, F. M. Farin, D. A. Nickerson, K. L. Edwards, D. Leonetti, M. J. McNeely, H. M. Viernes, S. E. Humphries, and W. Y. Fujimoto. 2004. Association of apolipoprotein A5 variants with LDL particle size and triglyceride in Japanese Americans. Biochim. Biophys. Acta. 1688: 1–9.[Medline]

115. Vohl, M. C., A. Tchernof, F. T. Dionne, S. Moorjani, D. Prud'homme, C. Bouchard, A. Nadeau, P. J. Lupien, and J. P. Despres. 1996. The apoB-100 gene EcoRI polymorphism influences the relationship between features of the insulin resistance syndrome and the hyper-apoB and dense LDL phenotype in men. Diabetes. 45: 1405–1411.[Abstract]

116. Couture, P., J. D. Otvos, L. A. Cupples, P. W. Wilson, E. J. Schaefer, and J. M. Ordovas. 1999. Association of the A-204C polymorphism in the cholesterol 7alpha-hydroxylase gene with variations in plasma low density lipoprotein cholesterol levels in the Framingham Offspring Study. J. Lipid Res. 40: 1883–1889.[Abstract/Free Full Text]

117. Okumura, K., H. Matsui, Y. Ogawa, R. Takahashi, K. Matsubara, H. Imai, A. Imamura, T. Mizuno, M. Tsuzuki, and Y. Kitamura. 2003. The polymorphism of the beta3-adrenergic receptor gene is associated with reduced low-density lipoprotein particle size. Metabolism. 52: 356–361.[CrossRef][Medline]

118. Hayaishi-Okano, R., Y. Yamasaki, K. Ohtoshi, T. Yasuda, N. Katakami, T. Hirano, G. Yoshino, Y. Kajimoto, and M. Hori. 2002. NAD (P) H oxidase p22 phox C242T polymorphism affects LDL particle size and insulin resistance in Japanese subjects. J. Atheroscler. Thromb. 9: 200–205.[Medline]

119. Gertow, K., C. Skoglund-Andersson, P. Eriksson, S. Boquist, K. Orth-Gomer, K. Schenck-Gustafsson, A. Hamsten, and R. M. Fisher. 2003. A common polymorphism in the fatty acid transport protein-1 gene associated with elevated post-prandial lipaemia and alterations in LDL particle size distribution. Atherosclerosis. 167: 265–273.[CrossRef][Medline]

120. Osgood, D., D. Corella, S. Demissie, L. A. Cupples, P. W. Wilson, J. B. Meigs, E. J. Schaefer, O. Coltell, and J. M. Ordovas. 2003. Genetic variation at the scavenger receptor class B type I gene locus determines plasma lipoprotein concentrations and particle size and interacts with type 2 diabetes: the Framingham Study. J. Clin. Endocrinol. Metab. 88: 2869–2879.[Abstract/Free Full Text]

121. Patsch, W., R. Ostlund, I. Kuisk, R. Levy, and G. Schonfeld. 1982. Characterization of lipoprotein in a kindred with familial hypercholesterolemia. J. Lipid Res. 23: 1196–1205.[Medline]

122. Slack, J., and G. L. Mills. 1970. Anomalous low density lipoproteins in familial hyperbetalipoproteinaemia. Clin. Chim. Acta. 29: 15–25.[CrossRef][Medline]

123. Schaefer, E. J., M. E. Brousseau, M. R. Diffenderfer, J. S. Cohn, F. K. Welty, J. O'Connor, Jr., G. G. Dolnikowski, J. Wang, R. A. Hegele, and P. J. Jones. 2001. Cholesterol and apolipoprotein B metabolism in Tangier disease. Atherosclerosis. 159: 231–236.[CrossRef][Medline]

124. Kuivenhoven, J. A., G. K. Hovingh, A. van Tol, M. Jauhiainen, C. Ehnholm, J. C. Fruchart, E. A. Brinton, J. D. Otvos, A. H. Smelt, A. Brownlee, A. H. Zwinderman, M. R. Hayden, and J. J. Kastelein. 2003. Heterozygosity for ABCA1 gene mutations: effects on enzymes, apolipoproteins and lipoprotein particle size. Atherosclerosis. 171: 311–319.[CrossRef][Medline]

125. Austin, M. A., M. C. King, K. M. Vranizan, and R. M. Krauss. 1990. Atherogenic lipoprotein phenotype. A proposed genetic marker for coronary heart disease risk. Circulation. 82: 495–506.[Abstract/Free Full Text]

126. Edwards, K. L., M. A. Austin, B. Newman, E. Mayer, R. M. Krauss, and J. V. Selby. 1994. Multivariate analysis of the insulin resistance syndrome in women. Arterioscler. Thromb. 14: 1940–1945.[Abstract/Free Full Text]

127. Edwards, K. L., B. Newman, E. Mayer, J. V. Selby, R. M. Krauss, and M. A. Austin. 1997. Heritability of factors of the insulin resistance syndrome in women twins. Genet. Epidemiol. 14: 241–253.[CrossRef][Medline]

128. Edwards, K. L., P. J. Talmud, B. Newman, R. M. Krauss, and M. A. Austin. 2001. Lipoprotein candidate genes for multivariate factors of the insulin resistance syndrome: a sib-pair linkage analysis in women twins. Twin Res. 4: 41–47.[CrossRef][Medline]

129. Juo, S. H., S. J. Bredie, L. A. Kiemeney, P. N. Demacker, and A. F. Stalenhoef. 1998. A common genetic mechanism determines plasma apolipoprotein B levels and dense LDL subfraction distribution in familial combined hyperlipidemia. Am. J. Hum. Genet. 63: 586–594.[CrossRef][Medline]

130. Jarvik, G. P., J. D. Brunzell, M. A. Austin, R. M. Krauss, A. G. Motulsky, and E. Wijsman. 1994. Genetic predictors of FCHL in four large pedigrees. Influence of ApoB level major locus predicted genotype and LDL subclass phenotype. Arterioscler. Thromb. 14: 1687–1694.[Abstract/Free Full Text]

131. Austin, M. A., H. Horowitz, E. Wijsman, R. M. Krauss, and J. Brunzell. 1992. Bimodality of plasma apolipoprotein B levels in familial combined hyperlipidemia. Atherosclerosis. 92: 67–77.[CrossRef][Medline]

132. Jiao, S., T. G. Cole, R. T. Kitchens, B. Pfleger, and G. Schonfeld. 1990. Genetic heterogeneity of plasma lipoproteins in the mouse: control of low density lipoprotein particle sizes by genetic factors. J. Lipid Res. 31: 467–477.[Abstract]

133. Singh, A. T., D. L. Rainwater, C. M. Kammerer, R. M. Sharp, M. Poushesh, W. R. Shelledy, and J. L. VandeBerg. 1996. Dietary and genetic effects on LDL size measures in baboons. Arterioscler. Thromb. Vasc. Biol. 16: 1448–1453.[Abstract/Free Full Text]

134. Rainwater, D. L., C. M. Kammerer, M. C. Mahaney, J. Rogers, L. A. Cox, J. L. Schneider, and J. L. VandeBerg. 2003. Localization of genes that control LDL size fractions in baboons. Atherosclerosis. 168: 15–22.[CrossRef][Medline]

135. Wu, L., S. Hunt, G. Afman, H. Nichols, T. Adams, J. Lalouel, and R. Williams. 1988. Genetic concordance of and exercise effects on low density lipoprotein subfractions in Utah twins (Abstract). Circulation 78 (Suppl.): II-481.

136. Dreon, D. M., H. A. Fernstrom, P. T. Williams, and R. M. Krauss. 2000. Reduced LDL particle size in children consuming a very-low-fat diet is related to parental LDL-subclass patterns. Am. J. Clin. Nutr. 71: 1611–1616.[Abstract/Free Full Text]

137. Zambon, A., S. S. Deeb, B. G. Brown, J. E. Hokanson, and J. D. Brunzell. 2001. Common hepatic lipase gene promoter variant determines clinical response to intensive lipid-lowering treatment. Circulation. 103: 792–798.[Abstract/Free Full Text]

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