SNX19 and cerebellar ataxia: Whereas biallelic mutations in the SNX14 gene are known to cause autosomal recessive spinocerebellar ataxia 20 (SCAR20), a disorder characterized by cerebellar atrophy, ataxia, and severe intellectual disability48,49, mutations in the SNX19 gene have not yet been shown to cause a Mendelian disorder50–55.