The novel somatic mutation, MEN1 c.1402_1405del GAGG, and LOH was identified in the parathyroid carcinoma tissue of II-3, and a novel somatic mutation, MEN1 c.286 C > T, was found in the thoracic neuroendocrine tumor of III-6. This evidence concerns the gene MEN1 and parathyroid gland carcinoma.