genetics

Last reviewed 01/2018

The SCA1 gene at chromosome 6p22-p23 is implicated in the pathogenesis of spinocerebellar atrophy type I.

A highly polymorphic and unstable CAG trinucleotide repeat has been found in the region of SCA1.

There is a direct correlation between the number of CAG repeats and the severity of the disease phenotype and the age of onset. Large numbers of repeats result in juvenile onset spinocerebellar atrophy type 1.

The number of repeats may increase down the generations of a family results in more severe and earlier disease. This is called genetic anticipation.