Genetic and secondary causes of severe HDL deficiency and cardiovascular disease

Abstract

Supplementary key words apoA-I ABCA1 lecithin:cholesterol acyltransferase lipoprotein lipase high density lipoprotein metabolism reverse cholesterol metabolism dyslipidemia genes in lipid disorders It has been concluded that genetic HDL deficiency is not causative for atherosclerotic cardiovascular disease (ASCVD), in contrast to genetic hypercholesterolemia associated with elevated levels of LDL cholesterol (LDL-C) or genetic hypertriglyceridemia (1, 2). This assessment has been reported in high-impact journals by a very large number of authors, representing some of the most prominent and well-known scientists in our field. The data generated stem from a very large number of subjects studied with and without ASCVD. The analyses, however, were based entirely on SNPs, mainly in intronic DNA regions, and excluded the four most important genes that regulate HDL cholesterol (HDL-C) levels: ABCA1, LCAT, APOA1, and LPL. The exclusions were justified by study findings that 1) genetic variations at the ABCA1, LCAT, APOA1, and LPL gene loci also affect TG and/or LDL-C levels and 2) an LIPC variant was not associated with ASCVD (1, In our view this justification is flawed. Our recent review of severe HDL deficiency has documented that patients with HDL-C levels <20 mg/dl in the absence of secondary causes may have premature ASCVD, especially if such patients are homozygous or compound heterozygous for mutations in the APOA1 or ABCA1 genes (3).