RET gemline testing for medullary thyroid carcinoma covered by national health insurance in Japan

Abstract

Medullary thyroid carcinoma （MTC） is divided into two types; hereditary form and sporadic form. Approximately 30% of patients are hereditary, and 70% are sporadic. Hereditary MTC is a part of clinical manifestations of multiple endocrine neoplasia type 2 （MEN2）. The causative gemline for MEN2 is RET oncogene and this gene is located on chromosome 10q11.2. More than 98% of MEN2 patients have RET germline mutations. To discriminate between hereditary and sporadic forms, RET gemline testing is strongly recommended for all patients with MTC. In addition, clinical subtypes of MEN2 （MEN2A, MEN2B and Familial medullary thyroid carcinoma） are strongly correlated with the position of the mutated RET codon. After RET gene testing had been performed as research level in Japan, the testing was approved as advanced medical technology in 2008. From April 2016, this genetic diagnosis has been covered by national health insurance. Here we comment in the topics of RET genetic diagnosis under national health insurance system in Japan.