PCSK9 and LDLR are known to interact with each other and both are medically important because mutations in both genes are associated with familial hypercholesterolemia (Abifadel et al., 2003; Abifadel et al., 2009a; Abifadel et al., 2009b; Abifadel et al., 2012). This evidence concerns the gene LDLR and familial hypercholesterolemia.