Spinocerebellar Ataxia 36 is a Frequent Cause of Hereditary Ataxia in Eastern Spain

BackgroundAutosomal dominant spinocerebellar ataxia 36 (SCA36) is caused by hexanucleotide repeat expansion in the NOP56 gene. ObjectivesTo assess frequency, clinical and genetic features of SCA36 in Eastern Spain. MethodsNOP56 expansion was tested in a cohort of undiagnosed cerebellar ataxia families (n = 84). Clinical characterization and haplotype studies were performed. ResultsSCA36 was identified in 37 individuals from 16 unrelated families. It represented 5.4% of hereditary ataxia patients. The majority were originally from the same region and displayed a shared haplotype. Mean age at onset was 52.5 years. Non-ataxic features included: hypoacusis (67.9%), pyramidal signs (46.4%), lingual fasciculations/atrophy (25%), dystonia (17.8%), and parkinsonism with evidence of dopaminergic denervation (10.7%). ConclusionsSCA36 is a frequent cause of hereditary ataxia in Eastern Spain, and is associated with a strong founder effect. SCA36 analysis should be considered prior to other studies, especially in AD presentations. Parkinsonism reported here broadens SCA36 clinical spectrum.