LDLRAP1 and familial hypercholesterolemia: LDLRAP1, which encodes LDL receptor adaptor protein 1, is another gene that very rarely can be implicated in FH.13 Variants in LDLRAP1 lead to an autosomal recessive form, also called ARH, clinically characterized by severe hypercholesterolemia and genetically recognized as a homozygous form of FH.