Polymorphism of trinucleotide repeats in non-translated regions of SCA8 and SCA12 genes: allele distribution in a Polish control group

Spinocerebellar ataxias are a group of neurodegenerative disorders caused by dynamic mutations of microsatellite repeats. Two novel forms of SCAs have been described recently: SCA8, with expansions of CTA/CTG repeats in 3'UTR of the SCA8 gene, and SCA12, caused by expansion of the CAG tract in 5'UTR of the SCA12/PP2R2B gene. Analysis of CTA/CTG and CAG polymorphism in those two genes was performed in a Polish control group consisting of 100 individuals without any neurological signs. The distribution and ranges of the number of non-pathogenic repeats were similar to those observed in other populations described previously. Expansion of CTA/CTG repeats in the SCA8 locus was found in 2 of 100 controls and in 5 probands among 150 pedigrees affected with unidentified ataxias. As such expanded alleles were also observed in their healthy relatives, the pathogenic role of expansions in the SCA8 gene remains uncertain.