New Horizons in the Pathogenesis, Pathophysiology and Treatment of Familial Hypercholesterolaemia

Familial Hypercholesterolaemia (FH) is an autosomal-dominant genetic disease and represents the most common genetic disorder: heterozygous 1/250 births, homozygous 1/300, 000 births. FH is characterized by high to very high low-density lipoprotein cholesterol (LDL-C), which is the main cause of increased incidence of premature atherosclerotic Cardiovascular Disease (CVD) or aortic stenosis.

The aim of the review was to investigate the pathogenesis and the pathophysiology of FH.

The most common (60-80%) FH cause is mutations of the LDL Receptor (LDLR) protein (6 classes with a different number of receptors and functionality). Moreover, mutations in apolipoprotein B (APOB) (<5%) and gain-of-function mutations of proprotein convertase subtilisin/kexin type 9 genes (PCSK9) (<1%) contribute to its pathogenesis. An Autosomal Recessive Hypercholesterolaemia (ARH) is another cause, very rare (1/2.500 births), mainly in Sardinia. The remaining patients with a clinical diagnosis of monogenic hypercholesterolaemia do not present any known genetic cause. Since FH is a significant public health problem, early diagnosis and treatment are of utmost importance. Recent studies demonstrated the influence of the LDLR mutation type in the FH phenotype, associating a more severe clinical phenotype and worse advanced CVD in patients with null mutation than those with receptor-defective mutations. This analysis completes the adequate clinical diagnosis.

Both homozygous and heterozygous FH are related to mutations of LDLR (mainly), APOB, PCSK9, while other rare forms exist. All aberrations lead to the impaired removal of LDL-C from the blood leading to its accumulation and subsequent CVD earlier than in the general population.