Slowly progressive spinocerebellar ataxia with extrapyramidal signs and mild cognitive impairment (SCA21).

Spinocerebellar ataxia 21 is a slowly progressive and mild ataxia associated with extrapyramidal signs. Affected subjects exhibit a moderate gait and limb ataxia variably associated with akinesia, tremor, rigidity, hyporeflexia, and mild cognitive impairment. The responsible gene has been assigned to a 19 Mbases interval on chromosome 7p in a single French family. No evidence of significant linkage to this locus was found in 21 other families obtained from the EUROSCA consortium. The locus interval contains several candidate genes that could be responsible for the disease. Direct sequencing of NDUFA4, PHF14, KIAA0960, ARLA4, ETV1, DGKB, HDAC9, FERD3L, ITGB8, and SP4 genes were performed, but all the direct mutation analyses were negative excluding pathogenic mutations associated with the disease. Therefore, the gene responsible for SCA21 remains to be identified.