Genetics of familial hypercholesterolemia

Abstract

Familial hypercholesterolemia is an inherited disorder characterized by abnormally high serum cholesterol levels from birth. For this reason, patients have a very high risk of suffering premature cardiovascular events. With a prevalence of 1 in 250, it is now considered one of the most frequent genetic diseases in the world. However, despite its high frequency and effective treatments, it continues to be under-treated and under-diagnosed worldwide. Familial hypercholesterolemia is an oligogenic disorder of lipid metabolism mainly determined by mutations inLDLRgene (90% of cases) and of autosomal dominant inheritance. Less frequently, mutations have been found in APOB, PCSK9, STAP1 and APOE genes (also of autosomal dominant inheritance) and in the LDLRAP1 gene (of autosomal recessive inheritance). In patients without mutations in these genes, the increase in their cholesterol can be explained by the sum of risk alleles in different loci, configuring a polygenic disease. This diversity of major mutations and common polymorphic variants lead to a wide spectrum of clinical presentations. The presence of mutations in the LDLR gene increases the risk of coronary events over twenty times. The identification of a pathogenic variant allows family cascade screening, which is the most cost-effective strategy for the identification of affected persons. That is why in recent years the importance of molecular diagnosis as a driver of medical intervention and family monitoring has been highlighted.