Hypercholesterolemia, familial, 1

Familial hypercholesterolemia (FH) is characterized by severely elevated LDL cholesterol (LDL-C) levels that lead to atherosclerotic plaque deposition in the coronary arteries and proximal aorta at an early age, leading to an increased risk for cardiovascular disease. Xanthomas (patches of yellowish cholesterol buildup) may worsen with age as a result of extremely high cholesterol levels. Xanthomas can occur around the eyelids and within the tendons of the elbows, hands, knees, and feet. In FH, the more common cardiovascular disease is coronary artery disease (CAD), which may manifest as angina and myocardial infarction; stroke occurs more rarely. Untreated men are at a 50% risk for a fatal or nonfatal coronary event by age 50 years; untreated women are at a 30% risk by age 60 years. An estimated 70%-95% of FH results from a heterozygous pathogenic variant in one of three genes (APOB, LDLR, PCSK9). FH is the most common inherited cardiovascular disease, with a prevalence of 1:200-250. FH likely accounts for 2%-3% of myocardial infarctions in individuals younger than age 60 years. In contrast, homozygous FH (HoFH) results from biallelic (homozygous or compound heterozygous) pathogenic variants in one of these known genes (APOB, LDLR, PCSK9). Most individuals with HoFH experience severe CAD by their mid-20s and the rate of either death or coronary bypass surgery by the teenage years is high. Severe aortic stenosis is also common.

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