SCA7 (Spinocerebellar Ataxia Type 7)

The diagnosis of SCA7 is established in a proband by the identification of a heterozygous abnormal CAG trinucleotide repeat expansion in ATXN7 by molecular genetic testing.

Spinocerebellar ataxia 7 (SCA7) is an inherited disease of the central nervous system that leads to impairment of specific nerve fibers carrying messages to and from the brain, resulting in degeneration of the cerebellum (the coordination center of the brain). SCA7 differs from most other forms of SCA in that visual problems, rather than poor coordination, are generally the earliest signs of the disease. Affected individuals have progressive changes in vision (which can result in blindness); symptoms of ataxia; slow eye movements; and mild changes in sensation or reflexes. Later symptoms include loss of motor control, unclear speech (dysarthria), and difficulty swallowing (dysphagia). SCA7 is caused by genetic changes in the ATXN7 gene and is inherited in an autosomal dominant manner.