Expanded CAG Repeats in ATXN1, ATXN2, ATXN3, and HTT in the 1000 Genomes Project

Background Spinocerebellar ataxia types 1, 2, 3 and Huntington disease are neurodegenerative disorders caused by expanded CAG repeats. Methods We performed an in-silico analysis of CAG repeats in ATXN1, ATXN2, ATXN3, and HTT using 30x whole-=genome sequencing data of 2504 samples from the 1000 Genomes Project. Results Seven HTT-positive, 3 ATXN2-positive, 1 ATXN3-positive, and 6 possibly ATXN1-positive samples were identified. No correlation was found between the repeat sizes of the different genes. The distribution of CAG alleles varied by ethnicity. Conclusion Our results suggest that there may be asymptomatic small expanded repeats in almost 0.5% of these populations. (c) 2020 International Parkinson and Movement Disorder Society

Automated summary

The study identified HTT-positive, ATXN2-positive, ATXN3-positive, and possibly ATXN1-positive samples in 0.5% of these populations, indicating the presence of asymptomatic small expanded repeats. There was no correlation between repeat sizes of different genes and the distribution of CAG alleles varied by ethnicity.