 The plasma PCSK9 concentration is higher in women compared to men, and the PCSK9 concentrations decrease with age in men but increase in women, suggesting that estrogen level most likely plays a role.PCSK9 gene expression can be regulated by sterol-response element binding proteins (SREBP-1/2), which also controls LDLR expression.PCSK9 may also have a role in the differentiation of cortical neurons.