Familial myasthenia gravis has rarely been reported. We recently treated two patients with myasthenia gravis in the same family.
Case 1 : A 41-year-old woman began to have bilateral blepharoptosis ten years ago. Myasthenia gravis was diagnosed. Because of gradually increasing general symptoms, she had an extensive thymectomy in 1987.
Histological examination showed involutional changes in the thymus with scattered germinal centers. Her anti-AchR-Ab level was 67 nmol/l before the operation, and 92 nmol/l after the operation. Ambenonium was given 10 mg/day before the operation, and the dose was decreased to 7.5 mg/day after the operation.
Case 2 : A 21-year-old man, the son of Case 1, began to have bilateral blepharoptosis and diplopia at the age of five. Ocular myasthenia gravis was diagnosed, and he was treated with an anticholinergic agent.
This family includes three persons with hyperthyroidism and one with hypothyroidism.
The mother's (Case 1) HLA was A2, Aw33, Bw44 and Bw46, and the son's (Case 2) was A2, A26, Bw35 and Bw46.