Familial Hypercholesterolemia: Genes and Beyond

Genetic disorders resulting in familial hypercholesterolemia (FH) include autosomal dominant hypercholesterolemia (ADH), polygenic hypercholesterolemia, as well as other rare conditions such as autosomal recessive hypercholesterolemia (ARH). All of these disorders cause elevations in low-density lipoprotein (LDL)-cholesterol (LDL-C) and, as a result, greatly increase the risk of cardiovascular disease (CVD). Genetic loci involved in ADH include the LDLR, which codes for the LDL receptor (LDLR), APOB, which codes for apolipoprotein B-100 (apoB-100), the major protein component of LDL, PCSK9, which codes for Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9), the low abundance circulatory protein that terminates the lifecycle of the LDLR, and apolipoprotein E (APOE), which is an important constituent of triglyceride rich lipoproteins. Importantly, a large percentage of people with the severe hypercholesterolemic phenotype do not possess a readily identifiable gene defect and many likely have polygenic hypercholesterolemia. Thus, identification of a specific genetic pathologic variant is not a necessary condition for the diagnosis of a genetic hypercholesterolemia. Several formal diagnostic criteria exist for FH and include lipid levels, family history, personal history, physical exam findings, and genetic testing. As all individuals with severe hypercholesterolemia are at high risk for CVD, treatment is centered on dietary and lifestyle modifications and early institution of...