Purpose of review: Low cholesterol syndromes were considered curiosities. The present article reviews some hypolipidaemic disorders and the drugs developed from the insights they provided.
Recent findings: Abetalipopoproteinaemia and hypobetalipoproteinaemia are associated with low cholesterol concentrations and caused by mutations in apolipoprotein (apo) B or microsomal transfer protein. This led to the development of mipomersen and lomitapide which are used to treat homozygous familial hypercholesterolaemia. Mutations in proprotein convertase subtilisin kexin-9 (PCSK9) can cause either high or low cholesterol. Loss of function PCSK9 mutations prompted the development of antibody therapies to PCSK9 which are now widely used to treat hypercholesterolaemia. Mutations in apolipoprotein C-3 and angiopoietin-like protein 3 (ANGPTL3) cause hypolipoproteinaemia and reduced triglycerides. Antisense therapies to apolipoprotein C-3 and antibodies to ANGPTL3 are in development to treat familial chylomicronaemia syndrome. Activating mutations in apoA-1 result in hyper-functioning high-density lipoprotein (HDL) and suggest that modifying HDL turnover may reduce cardiovascular disease (CVD) risk.
Summary: Orphan lipid disorders have provided insights into mechanisms involved in lowering cholesterol levels and the potential safety and efficacy of interventional processes. They have been not only enabled development of drugs to treat rare lipid disorders but also those finding wider use in general lowering of CVD risk.