Multiple endocrine neoplasia type 1 is not rare in Japan.

Multiple endocrine neoplasia type 1 (MEN 1) is rarely reported in Japanese and other oriental populations. To examine if there is a racial difference in the prevalence of MEN 1, we initiated extensive work on patients with endocrine tumors for additional lesions, and annual screening of family members of affected patients. In a four-year study, eleven asymptomatic patients were found by family screening, and the number of patients with MEN 1 in our clinics increased from 16 to 38. Estimated prevalence of MEN 1 was no less than 0.018/1000. MEN 1 may not be as rare as had been thought in Japanese, and the prevalence of MEN 1 in Japanese would not be significantly different from that of Caucasians. Systemic surveillance and extensive screening of family members are required for early detection and management of patients.