 The most common genetic defects in FH are "LDLR" mutations (prevalence 1 in 500, depending on the population), ApoB mutations (prevalence 1 in 1000), "PCSK9" mutations (less than 1 in 2500) and "LDLRAP1".The related disease sitosterolemia, which has many similarities with FH and also features cholesterol accumulation in tissues, is due to "ABCG5" and "ABCG8" mutations.The LDL receptor gene is located on the short arm of chromosome 19 (19p13.1-13.3).