多内分泌腫虜MEN 2A型, 2B型の分子遺伝学的研究の動向 (特集 : 甲状腺系の分子内分泌学）

Multiple endocrine neoplasia (MEN) type 2A (MEN 2A) and type 2B (MEN 2B) are dominantly inherited with a predisposition to endocrine tumors. The responsible genes for MEN 2A and 2B have recently been localized to chromosome 10q 11.2 by genetic and physical mapping. The DNA segment encompasses the RET proto-oncogene. This is a receptor tyrosine kinase gene, which is expressed in medullary thyroid carcinoma and pheochromocytoma. Point mutations in the cysteine-rich domain of the RET were demonstrated in patients with MEN 2A. The cosegregation of these mutations and disease in MEN 2A families indicates that they possess a predisposition endocrine organs to develop into tumors. Biological assesment of the mutant forms in cell culture and trans­genic mouse lines should provide further insight as to the role of the RET in the tumor development.