Severe symptoms of 16q-ADCA coexisting with SCA8 repeat expansion

We report a family with 16q-ADCA(16q 22.1 linked autosomal dominant cerebellar ataxia) coexisting with SCA8 repeat expansion. The brothers in this family presented with pyramidal signs, tremor, myoclonus and mental retardation in addition to cerebellar symptom in childhood. They showed both C-to-T substitution puratrophin-1 gene and an expanded allele of the SCA8 gene in the brothers and their father. These siblings presented with atypical symptoms and early onset age as16q-ADCA. Although it remains controversial whether the expanded SCA8 allele is associated with cerebellar symptoms, the coexistence of SCA8 repeat expansion with SCA6 was reported previously. Pure or predominant cerebellar symptoms were found in patients with SCA8, SCA6 and 16q-ADCA. In addition, common findings in neuropathology of SCA8, SCA6 and 16q-ADCA have been reported. We suppose that coexistence of SCA8 repeat expansion with 16q-ADCA may be involved in the pathogenesis and severe symptoms in this family.