The clinical and genetic characteristics of spinocerebellar ataxia type 7 (SCA 7) in three Black South African families.

Abstract

Spinocerebellar ataxia type 7 is a rare autosomal dominant neurodegenerative disorder characterized by progressive cerebellar and retinal degeneration, described in various population groups in the literature. This is the first description from South Africa. The objective was to document the clinical and genetic characteristics of our patients and to determine concordance with other described cases. The index cases were identified clinically on the basis of the typically described features of progressive ataxia with visual failure due to progressive cerebellar and retinal/macular degeneration. Associated neurological disturbances were documented. Where possible, and available, family members were assessed and pedigrees were delineated. Molecular tests for SCA expansions were determined in the index cases. Three pedigrees of SCA 7 were identified. The patients were all Black South Africans. The genetic and clinical characteristics are typical for SCA 7. SCA 7 is a rare distinct neurodegenerative disorder characterized by trinucleotide expansion.