Spinocerebellar Ataxia type 29 in a family of Māori descent

Mutations in the Inositol 1,4,5-Trisphosphate Receptor Type 1 (ITPR1) gene cause spinocerebellar ataxia type 29 (SCA29), a rare congenital-onset autosomal dominant non-progressive cerebellar ataxia. The Māori, indigenous to New Zealand, are an understudied population for genetic ataxias.

We investigated the genetic origins of spinocerebellar ataxia in a family of Māori descent consisting of two affected sisters and their unaffected parents. Whole exome sequencing identified a pathogenic variant, p.Thr267Met, in ITPR1 in both sisters, establishing their diagnosis as SCA29.

We report the identification of a family of Māori descent with a mutation causing SCA29, extending the worldwide scope of this disease. Although this mutation has occurred de novo in other populations, suggesting a mutational hotspot, the children in this family inherited it from their unaffected mother who was germline mosaic.