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Modification of Huntington's disease by short tandem repeats
Journal article   Open access   Peer reviewed

Modification of Huntington's disease by short tandem repeats

Eun Pyo Hong, Eliana Marisa Ramos, N Ahmad Aziz, Thomas H Massey, Branduff McAllister, Sergey Lobanov, Lesley Jones, Peter Holmans, Seung Kwak, Michael Orth, …
Brain communications, Vol.6(2), fcae016
03/01/2024
DOI: 10.1093/braincomms/fcae016
PMCID: PMC10917446
PMID: 38449714
url
https://doi.org/10.1093/braincomms/fcae016View
Published (Version of record) Open Access

Abstract

Abstract Expansions of glutamine-coding CAG trinucleotide repeats cause a number of neurodegenerative diseases, including Huntington's disease (HD) and several of the spinocerebellar ataxias (SCAs). In general, age-at-onset of the polyglutamine diseases is inversely correlated with the size of the respective inherited expanded CAG repeat. Expanded CAG repeats are also somatically unstable in certain tissues, and age-at-onset of HD corrected for individual HTT CAG repeat length (i.e., residual age-at-onset), is modified by repeat instability-related DNA maintenance/repair genes as demonstrated by recent genome-wide association studies (GWAS). Modification of one polyglutamine disease (e.g., HD) by the repeat length of another (e.g., ATXN3, CAG expansions in which cause SCA3) has also been hypothesized. Consequently, we determined whether age-at-onset in HD is modified by the CAG repeats of other polyglutamine disease genes. We found that the CAG measured repeat sizes of other polyglutamine disease genes were polymorphic in HD participants but did not influence HD age-at-onset. Additional analysis focusing specifically on ATXN3 in a larger sample set (n = 1,388) confirmed the lack of association between HD residual age-at-onset and ATXN3 CAG repeat length. Additionally, neither our HD onset modifier GWAS single nucleotide polymorphism (SNP) data nor imputed short tandem repeat (STR) data supported involvement of other polyglutamine disease genes in modifying HD. By contrast, our GWAS based on imputed STRs revealed significant modification signals for other genomic regions. Together, our STR GWAS show that modification of HD is associated with STRs that do not involve other polyglutamine disease-causing genes, refining the landscape of HD modification and highlighting the importance of rigorous data analysis, especially in genetic studies testing candidate modifiers.

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