Large SGCE deletion contributes to Taiwanese myoclonus–dystonia syndrome

We report three novel deletions of the SGCE gene in three families with myoclonus–dystonia (M–D) syndrome in Taiwan. Their clinical characteristics included: early onset, dominant myoclonus and dystonia in the neck, trunk and upper limbs. By direct sequencing of the SGCE gene coding regions, we identified a small heterozygous deletion (c.842delA) in exon 7 of the three sibs and asymptomatic father in the first family and an eight-base heterozygous deletion (c.524_531del) in exon 5 of the mother and a daughter in the second family. Using multiple ligation-dependent probe amplification (MLPA), a large heterozygous deletion of 2–11 exons was identified in the father and a son in the third family which was undetected by initial sequencing. It is the largest intragenic deletion ever reported. In conclusion, we have identified three novel mutations of SGCE in the respective three M–D families. The large deletion was responsible for one third of these M–D families which might implicate an important contribution to Taiwanese M–D syndrome. We suggest that the contribution of large deletion should be further verified in a large cohort of patients with M–D syndrome in Han Chinese.