Effort Angina in a Middle-Aged Woman With Abnormally High Levels of Serum High-Density Lipoprotein Cholesterol A Case of Cholesteryl-Ester Transfer Protein Deficiency

HDL-cholesterol modulation and its impact on the management of cardiovascular risk

There is strong epidemiological evidence that HDL-cholesterol (HDL-C) is an independent cardiovascular risk factor. A low HDL-C is a common finding in the general population, and is a feature of metabolic syndrome, the prevalence of which is increasing globally. The importance of HDL-C as a coronary risk factor is generally accepted, and has been incorporated into most of the commonly applied risk engines. There are several causes of a low HDL-C, including rare genetic abnormalities, and more common conditions associated with lifestyle and drug therapy. Not all of these are associated with an increased risk of coronary disease. A better understanding of HDL metabolism and the mechanisms by which it may exert its protective effects has revealed why this may be the case. New therapeutic targets have also been identified that may allow HDL-C to be raised in patients with low levels. However, good clinical endpoint studies are still required to enable the setting of absolute target values for HDL-C in patients at high cardiovascular risk.

CETP genotypes and HDL-cholesterol phenotypes in the HERITAGE Family Study

Associations between cholesteryl ester transfer protein (CETP) polymorphisms and high-density lipoprotein cholesterol (HDL-c) levels before and after 20 wk of endurance training were investigated in the HERITAGE Family Study. Plasma HDL-c, HDL2-c, HDL3-c, and apolipoprotein (apo)A1 levels were measured, and 13 CETP single nucleotide polymorphisms (SNPs) were genotyped in 265 blacks and 486 whites. Three haplotypes defined by SNPs at the −1337, −971, and −629 sites were strongly associated with baseline HDL-c levels in whites. Both C−1337T and C−629A were associated with baseline HDL-c ( P < 0.001) and apoA1 ( P < 0.01) when tested separately. However, only C−629A remained significant in a combined model. G−971A was not associated with HDL phenotypes, but showed significant interactions with C−629A ( P = 0.002) on baseline traits. Genotype-by-sex interactions were observed at the −629 locus for HDL3-c ( P = 0.004) and apoA1 ( P = 0.02) training responses in whites. In women, the −629 A/A homozygotes showed greater increases in HDL3-c ( P = 0.02) and apoA1 ( P = 0.02) levels than the other genotypes. Finally, apolipoprotein E (APOE) genotype and the CETP C−629A locus contributed independently and in additive fashion to the HDL traits, explaining 6.0–8.8% of the variance. The CETP −1337T and −629A alleles are associated with higher baseline HDL-c and apoA1 levels. The beneficial effects of endurance training on plasma HDL3-c and apoA1 levels are evident in white women homozygous for the −629A allele. The CETP and APOE genotypes account for up to 9% of the variance in HDL-c phenotypes in the HERITAGE Family Study.

The two novel CETP mutations Gln87X and Gln165X in a compound heterozygous state are associated with marked hyperalphalipoproteinemia and absence of significant coronary artery disease

High levels of high-density lipoprotein cholesterol (HDL-C) occur with cholesteryl ester transfer protein (CETP) deficiency. However, the extent to which CETP deficiency states may be associated with protection against coronary artery disease (CAD) has been controversial. We evaluated a Greek pedigree with high levels of HDL-C and no history of premature CAD. The proband, a 45-year-old male with an HDL-C of 194 mg/dl with absent CETP activity, was heterozygous for two novel CETP mutations (Q87X and Q165X). A 64-slice multidetector CT scan revealed minimal (<10%) narrowing of the proximal left anterior descending artery without any other evidence of coronary atherosclerosis. In contrast to previous studies, these data suggest that complete CETP deficiency does not promote premature atherosclerosis. However, it remains unclear as to whether the relative lack of coronary atherosclerosis was the direct consequence of CETP deficiency and/or the lack of traditional CAD risk factors.