Rapidly progressing retinal dystrophy in Spinocerebellar Ataxia 7 (SCA7): A case report of three brothers

SCA7, an autosomal dominant neurodegenerative disorder with retinal degeneration, is caused by CAG repeat expansion usually >36 in the ATXN7gene1,2. The ATXN7, normally <17 repeats, is responsible for chromatin remodeling through deubiquination to enhance transcription. Aggregates of expanded ATXN7complexes decrease deubiquination and create toxicity, leading to early cell death affecting retinal photoreceptors and cerebellum. These abnormal repeats show anticipation with the potential for marked expansion in subsequent generations, leading to severe disease. We present a family with SCA7 in whom very slight variations in expansion lead to devastating phenotypes.