Background and aim: HDL-cholesterol (HDL-C) is inversely related to the risk of ischemic heart disease. Many genes are reported to affect HDL-C serum levels in both hyperlipidemic and normolipidemic populations, though the data are controversial. We examined the effect of common gene polymorphisms known to interfere with HDL-C metabolism (apolipoprotein E, cholesterol ester transfer protein and apolipoprotein A-IV gene polymorphisms) on HDL-C plasma levels in normolipidemic subjects.
Methods and results: The study population consisted of 200 normolipidemic individuals visiting our clinic for a routine check-up. None of the above gene polymorphisms affected HDL-C levels in our population. However, participants carrying the allele E4 of the apolipoprotein (apo) E gene, the allele B1 of the TaqIB polymorphisms in the cholesterol ester transfer protein (CETP) gene and the allele T of the apoA-IV gene (A to T polymorphism at site 347) (n = 28) had statistically significantly lower HDL-C levels compared to those not carrying the above allele combination (0.99+/-0.33 vs 1.28+/-0.35 mmol/L, p = 0.04).
Conclusion: In this study, we describe a subgroup of normolipidemic individuals with low HDL-C levels due to genetic variability, and we discuss the underlying possible mechanisms involved.