Homozygous FH can be classified as: a- Real homozygous (HoFH): when the same mutation affects both alleles of one of the major FH-related genes (LDLR, APOB, or PCSK9); b- Compound heterozygous (cHeFH): when different mutations located on different alleles affect one of the major FH-associated genes; c- Combined heterozygous: when different mutations affect two different FH-related genes (Masana et al., 2019). The gene discussed is PCSK9; the disease is familial hyperaldosteronism.