Journal of neurology, neurosurgery, and psychiatry
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Myasthenia gravis in one member each of two sets of twins is described. A 17 year old girl developed generalized myasthenia gravis at the age of 14 years, while her monozygotic twin sister has remained in good health during a three year period of observation. ⋯ Both members of twins were affected in five sets of monozygotic twins and one set of twins with undetermined zygosity, and only one twin was affected in the remaining sets of twins. Occurrence of myasthenia gravis in both members of monozygotic twins and in none of dizygotic twins, and frequent familial occurrence of the disease suggest the role of a genetic factor in the pathogenesis of this disease.