Familial autoimmune myasthenia gravis and thymoma: occurrence in two brothers.

At ages 31 and 42 years, two brothers presented with clinical, pharmacologic, electrophysiologic, and immunologic characteristics of autoimmune myasthenia gravis. At thymectomy, both had histologic findings of epithelial thymoma. HLA analysis revealed A2, A3, B7, and B39 antigens in one patient and A3, A24, B7, and B40 antigens in the other. Familial myasthenia gravis with thymoma has not been described previously. Familial thymoma has been rarely reported, but never with myasthenia gravis.