Submitted on September 12, 2006
Revised on December 22, 2006
Accepted on December 27, 2006
Cholesteryl ester transfer protein and hyperalphalipoproteinemia in caucasians
Wim A. van der Steeg, G. Kees Hovingh, Anke H. E. M. Klerkx, Barbara A. Hutten, Inge C. Nootenboom, Johnnes H. M. Levels, Arie van Tol, Gees M. Dallinga-Thie, Aeilko H. Zwinderman, John J. P. Kastelein, and Jan Albert Kuivenhoven
Vascular Medicine, Academic Medical Center, Room F4-159.2, Amsterdam 1100 DD
Corresponding Author: w.a.vandersteeg{at}amc.uva.nl
It is unclear whether cholesteryl ester transfer protein (CETP) contributes to HDL cholesterol (HDL-C) levels in hyperalphalipoproteinemia (HALP) in Caucasians. Moreover, even less is known about the effects of hereditary CETP deficiency in non-Japanese. We have studied 95 unrelated Caucasian individuals (46% male) with HDL-C levels averaging 2.35 ± 0.42 mmol/l. Unlike findings in Japanese subjects with HALP, no correlations between CETP concentration or activity and HDL-C were identified in our cohort. Screening for CETP gene defects in this cohort led to the identification of heterozygosity for a novel splice site mutation in one individual. CETP mRNA analysis of adipose tissue revealed that 20% of the CETP mRNA pool consisted of the anticipated alternatively spliced CETP mRNA. 25 heterozygotes for this mutation showed reductions of CETP concentration (-40%) and CETP activity (-50%), and a 35% increase of HDL-C compared to family controls (matched for age, gender and body mass index). The heterozygotes presented with an isolated high HDL-C, while the remaining 94 HALP subjects exhibited a typical high HDL-C and low triglyceride phenotype. The increase of HDL-C in the CETP deficient heterozygotes was primarily due to elevated LpAI:AII levels, contrasting with a rise in both LpAI and LpAI:AII in the other group. This study suggests the absence of a relationship between CETP and HDL-C levels in Caucasians with HALP. The data furthermore indicate that genetic CETP deficiency is rare amongst Caucasians and that this disorder presents itself with a phenotype that is different from subjects with HALP who have no mutation in the CETP gene.