The C679X mutation in PCSK9 is present and lowers blood cholesterol in a Southern African population

Objective: Missense mutations in the proprotein convertase subtilisin/kexin type 9 gene (PCSK9) can cause familial hypercholesterolemia. However, two nonsense variants of PCSK9, Y142X and C679X, found in ∼2% of black American subjects, are associated with a 28% reduction in mean low density lipoprotein (LDL)-cholesterol. We sought to determine the frequency and effect of these nonsense variants in an African population. Methods and results: PCSK9 genotypes were determined in 653 black African women attending two antenatal clinics in Zimbabwe. C679X occurred in 3.7% of subjects and was associated with a 27% reduction in LDL-cholesterol (1.6 ± 0.3 mmol/L versus 2.2 ± 0.7 mmol/L in non-carriers). We did not observe the Y142X variant. Conclusions: Our results show that the PCSK9 C679X variant has a marked cholesterol-lowering effect.