A genome-wide linkage scan identifies multiple chromosomal regions influencing serum lipid levels in the population on the Samoan islands

Karolina Aberg, Feng Dai, Guangyun Sun, Ember D. Keighley, Subba Rao Indugula, Linda Bausserman, Satupaitea Viali, John Tuitele, Ranjan Deka, Daniel E. Weeks, and Stephen T. McGarvey

Professor of Community Health and Anthropology, University of Pittsburgh, Pittsburgh, PA 15261

Corresponding Author: Stephen_McGarvey{at}brown.edu

Abnormal lipid levels are important risk factors for cardiovascular diseases. We conducted genome-wide variance component linkage analyses to search for loci influencing total cholesterol (TC), low-density lipoprotein (LDL), high density lipoprotein (HDL) and triglyceride (TG), in families residing in American Samoa and Samoa, as well as in a combined sample from the two polities. To account for environmental variation, we adjusted the traits for a number of environmental covariates such as smoking, alcohol consumption, physical activity and material life style. We found suggestive univariate linkage with LOD scores greater than three for LDL on 6p21-p12 (LOD 3.13) in Samoa and on 12q21-q23 (LOD 3.07) in American Samoa. Furthermore, in American Samoa on 12q21 we detected genome-wide linkage (LODeq 3.38) to the bivariate trait TC-LDL. Telomeric of this region, on 12q24, we found suggestive bivariate linkage to TC-HDL (LODeq 3.22) in the combined study sample. In addition, we detected suggestive univariate linkage (LOD 1.9 - 2.93) on chromosome 4p-q, 6p, 7q, 9q, 11q, 12q 13q, 15q, 16p, 18q, 19p, 19q and Xq23 and suggestive bivariate linkage (LODeq 2.05 – 2.62) on chromosome 6p, 7q, 12p, 12q and 19p-q. In conclusion, chromosome 6p and 12q may host promising susceptibility loci influencing lipid levels; however, the low degree of overlap between the three study samples strongly encourages further studies of the lipid-related traits.

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