[SCA-7. Cone-rod dystrophy in the context of an hereditary ataxia]

A 21-year-old male presented with bilateral loss of visual acuity within the last year, and cerebellar ataxia since childhood. Two members of his family had a similar disorder. Examination showed bilateral central scotomas, as well as an electroretinogram pattern and optic coherence tomography images consistent with cone-rod dystrophy. Molecular analysis by PCR amplification and genotyping of the SCA7 gene established the diagnosis of SCA-7.

SCA-7 is a polyglutamine expansion disorder and the only spinocerebellar ataxia that shows a cone-rod dystrophy phenotype, which probably results from interference with the action of specific cone-rod genes.