The HeFH and HoFH disorders are caused by autosomal dominant mutations in LDLR (LDL receptor), APOB (apolipoprotein B100), and PCSK9 (proprotein convertase subtilisin/kexin type 9) genes (Nordestgaard et al., 2013; Gidding et al., 2015). The gene discussed is LDLR; the disease is homozygous familial hypercholesterolemia.