FMTC, MEN2A, and Waardenburg syndrome families accounted for 41% (16/39) and 31% (12/39), respectively, of the total; FMTC/MEN2A and Waardenburg syndrome patients accounted for 39% (29/74) and 31% (29/73) of the total, respectively. The gene discussed is RET; the disease is Waardenburg syndrome.