The OPCA pattern was identified as MSA-C in a few dominant ataxias (SCA1-3, SCA7, SCA34, SCA36, DRPLA), two recessive ataxias (BNS and SCAR7) and the X-linked ataxia associated with the PRPS1 gene mutation. This evidence concerns the gene PRPS1 and multiple system atrophy, cerebellar type.