Familial hypercholesterolemia--epidemiology, diagnosis, and screening.

Familial hypercholesterolemia is among the commonest inherited metabolic disorders and is characterized by severely elevated LDL cholesterol levels. Mutations in four genes have been noted in patients with familial hypercholesterolemia (FH): LDL receptor (most common), apolipoprotein B (Apo B), proprotein convertase subtilin/kexin 9 (PCSK9), and low-density lipoprotein receptor adaptor protein (LDLRAP). In most cases, inheritance is autosomal co-dominant with homozygotes having double the LDL cholesterol levels of heterozygotes. Autosomal recessive inheritance is rare. The prevalence of the heterozygous state has been estimated at 1 in 200 to 1 in 500 and of the homozygous state from 1 in 160,000 to 1 in 1,000, 000. Three formal diagnostic criteria have been proposed to diagnose FH in practice-MedPed, Simon Broome, and Dutch Lipid Clinic Network. The role of genetic testing and cascade screening among families is discussed in this review.