Recent advance in research of benign adult familial myoclonus epilepsy (BAFME): Is BAFME a progressive disorder?

Abstract

Benign adult familial myoclonus epilepsy (BAFME) is an adult onset, autosomal dominant disease characterized by cortical tremor and infrequent generalized seizures. BAFME was considered as non-progressive, but cortical tremor worsened in some of the aged patients. We investigated the disease progression of BAFME. Cortical tremor significantly worsened and amplitudes of giant somatosensory evoked potential significantly increased with age in BAFME. These findings suggest that a progressive increase of cortical hyperexcitability causes exaggeration of cortical tremor. The clinical anticipation, defined as earlier onset age of either cortical tremor or generalized seizures or new appearance of those symptoms in the next generation, was observed in all studied BAFME families. In addition, a higher degree of clinical anticipation was associated with maternal transmission than with paternal transmission. Despite a unknown causative gene for BAFME, our finding suggests that BAFME and diseases with unstable expanding repeats including those in non-coding regions, might share a similar molecular mechanism because such diseases often show clinical anticipation with maternal transmission. As mentioned above, at least some part of the symptoms and pathophysiology progress with aging or over generation in BAFME.