[Progressive myoclonic epilepsy in two brothers: genetic testing in the younger brother and pathological examination in the elder brother].

We report progressive myoclonic epilepsy in two brothers. The younger brother was diagnosed with progressive myoclonic epilepsy type 1 (EPM1) by genetic testing, and the elder brother underwent pathological examination. The parents were cousins. Both brothers presented with epileptic seizures in their early teens, followed by progressive cognitive impairment and cerebellar ataxia. In later life, epileptic seizures became intractable. The elder brother died at age 71, and the younger brother died at age 63. Genetic examination of the younger brother revealed a mutation in the CSTB gene. Pathological examination of the elder brother revealed cerebellar degeneration, mainly characterized by the loss of granule and Purkinje cells, as well as frontotemporal lobe atrophy, findings consistent with EPM1. However, the immunohistochemical findings differed from those in the previously reported case, suggesting that they may reflect a family-specific genetic background.