In three families second germline mutations were detected: Cys620Phe (exon 10) in MEN2A family, Met918Thr (exon 16) in MEN2B family, and Ser649Leu (exon 11) in HSCR patient.
In this report, we describe a new kindred in which the MEN2 and HSCR phenotypes are associated with a single C620S point mutation at one of the cysteine codons of the extracellular domain of the ret protooncogene.