Relationships Between Plasma PCSK9 Levels, LDL-cholesterol Concentrations and Lipoprotein (a) Levels in Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal codominant single gene disorder caused by mutations in the LDL receptor gene (LDLR) that disrupt the normal clearance of LDL particles from the plasma. Heterozygous patients (HeFH) present a two- to three-fold raise in plasma LDL-cholesterol (LDL-C) concentrations and coronary artery disease occurs earlier among HeFH carrying negative-receptor (NR) mutations as compared with HeFH subjects carrying defective-receptor (DR) variants. Proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates LDL-C levels by binding to LDLR and by enhancing its intracellular degradation. The objective of this study is to examine to what extent variations in LDL-C and Lipoprotein (Lp) (a) concentrations are related to PCSK9 levels in a large French-Canadian cohort of HeFH subjects. The primary hypothesis is that that PCSK9 levels have a significant impact on LDL-C concentration variability and are associated with Lp(a) levels.