Increased clinical anticipation with maternal transmission in benign adult familial myoclonus epilepsy in Japan.

We recently reported clinical anticipation in Japanese families with benign adult familial myoclonus epilepsy (BAFME). However, it remains unknown whether clinical anticipation is predominantly associated with paternal or maternal transmission. We investigated the relationship between gender of the transmitting parent and clinical anticipation in nine BAFME families. Clinical anticipation regarding either cortical tremor or generalised seizures was observed in all 12 parent/child pairs (8 mother/child pairs and 4 father/child pairs). Moreover, a higher degree of clinical anticipation was associated with maternal transmission than with paternal transmission (p=0.03). Although a causative gene for BAFME still remains unknown, 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.