RET and familial medullary thyroid carcinoma: MEN2A can be classified into 4 variants, including classical MEN2A (~60–70% of MEN2A cases), MEN2A with cutaneous lichen amyloidosis (CLA) (~9%), MEN2A with Hirschsprung disease (HD) (~7%), and familial MTC (FMTC; OMIM #155240) (~15%) (2).