De novo RET proto oncogene mutation in a patient with multiple endocrine neoplasia type 2B

We report a case of multiple: endocrine neoplasia type 2B (MEN 2B) with de nova RET proto-oncogene mutation, The patient, a 23-year-old Taiwanese woma n, was admitted for treatment of recurrent medullary thyroid cancer (MTC) 7 years after a total thyroidectomy. Mucosal neuromas and marfanoid appearan ce were also noted. Because MEN 2B was suspected, the patient and her famil y members underwent genetic analysis, A heterozygous germline mutation at c odon 918 (ATG --> ACG) of the proto-oncogene RET was detected in the patien t. This mutation was considered de novo, as it was not detected in either o f her parents or her siblings. he patient underwent surgery for removal of the recurrent tumor. Although no pheochromocytoma was noted, regular follow -up is necessary because of persistent hypercalcitoninemia.