RET and multiple endocrine neoplasia type 2: Combinations of two mutations on the same allele have previously been reported in other diseases inherited as autosomal dominant mode such as a missense (p.N543H) mutation and an in-frame 9-bp deletion (2393del9) of low-density lipoprotein receptor gene in familial hypercholesterolaemia23 and missense mutations at p.V804M and p.Y806C of RET proto-oncogene in multiple endocrine neoplasia type 2B (MEN2B)24,25.