Spinocerebellar ataxias (SCAs) comprise a large group of heterogeneous neurodegenerative disorders inherited in an autosomal dominant fashion. To date, 40 SCAs have been described. The most common ones are due to CAG repeat expansions in the coding regions of the respective genes (SCAs 1, 2, 3, 6, 7 and 17). In most cases, symptoms appear in the third to fifth decade.
SCA1, SCA2 and SCA3 have been found in many regions of India, although SCA1 is more common in South India and SCA3 in the Bengalis of East India.
SCA12 was first reported in an American family of German descent. The rest of the reported families are of Indian descent, majority of which belong to the Agarwal community.