[Multiple endocrine neoplasia type 2 in Japan: large-scale analysis of data from the MEN consortium of Japan].

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal, dominantly inherited disease characterized by medullary thyroid carcinoma, pheochromocytoma, and primary hyperparathyroidism and is divided into types 2A and 2B. Familial medullary thyroid carcinoma (FMTC) is characterized by the presence of medullary thyroid carcinoma alone in family members and is considered to be one of the subtypes of MEN2. Clinical and genetic data on 505 Japanese patients from 275 MEN2 or FMTC families registered at 54 medical institutions were collected by the MEN Consortium of Japan. The diagnosis was MEN2A in 343 (67.9%) patients, MEN2B in 29 (5.7%), FMTC in 103 (20.4%), and unclassified in 30 (5.9%). Medullary thyroid carcinoma was found in 91.2% of patients (437/479), pheochromocytoma in 45.6% (212/465), and primary hyperparathyroidism in 8.1% (37/457). RET genetic testing was performed in 410 patients, and the germline RET mutation was found in 98.8% (397/402).