Plasma PCSK9 levels correlate with cholesterol in men but not in women

Proprotein convertase subtilisin kexin-like 9 (PCSK9) is a secreted glycoprotein that negatively regulates low density lipoprotein receptor (LDLR) levels. Several single nucleotide polymorphisms (SNPs) in PCSK9 have been linked to autosomal dominant hypercholesterolemia (ADH). Conversely, hypocholesterolemia associates with both 'loss of function' nonsense and missense SNPs in PCSK9. We examined the association of plasma PCSK9 with lipoprotein parameters in 182 normolipidemics. For men (n = 98) plasma PCSK9 averaged 6.08 ± 1.96 μg/ml and Spearman analysis revealed significant correlation between it and total cholesterol (TC), LDLC, and TC/high density lipoprotein (HDLC) (r = 0.276, 0.282, and 0.228, respectively). For women (n = 84) plasma PCSK9 averaged 6.46 ± 1.99 μg/ml having no correlation with TC, LDLC or TC/HDLC. The ratio of plasma PCSK9/LDLC increased in men carrying 'loss of function' PCSK9 variations. Our results suggest a gender difference in PCSK9 regulation and function with PCSK9 correlated to TC and LDLC in men but not women.