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Exome sequencing of individuals with Huntington's disease implicates FAN1 nuclease activity in slowing CAG expansion and disease onset
Journal article   Open access   Peer reviewed

Exome sequencing of individuals with Huntington's disease implicates FAN1 nuclease activity in slowing CAG expansion and disease onset

Branduff McAllister, Jasmine Donaldson, Caroline S Binda, Sophie Powell, Uroosa Chughtai, Gareth Edwards, Joseph Stone, Sergey Lobanov, Linda Elliston, Laura-Nadine Schuhmacher, …
Nature neuroscience, Vol.25(4), pp.446-457
04/2022
DOI: 10.1038/s41593-022-01033-5
PMCID: PMC8986535
PMID: 35379994
url
https://doi.org/10.1038/s41593-022-01033-5View
Published (Version of record) Open Access

Abstract

The age at onset of motor symptoms in Huntington's disease (HD) is driven by HTT CAG repeat length but modified by other genes. In this study, we used exome sequencing of 683 patients with HD with extremes of onset or phenotype relative to CAG length to identify rare variants associated with clinical effect. We discovered damaging coding variants in candidate modifier genes identified in previous genome-wide association studies associated with altered HD onset or severity. Variants in FAN1 clustered in its DNA-binding and nuclease domains and were associated predominantly with earlier-onset HD. Nuclease activities of purified variants in vitro correlated with residual age at motor onset of HD. Mutating endogenous FAN1 to a nuclease-inactive form in an induced pluripotent stem cell model of HD led to rates of CAG expansion similar to those observed with complete FAN1 knockout. Together, these data implicate FAN1 nuclease activity in slowing somatic repeat expansion and hence onset of HD.
Age of Onset Endodeoxyribonucleases - genetics Endodeoxyribonucleases - metabolism Exodeoxyribonucleases - genetics Exodeoxyribonucleases - metabolism Exome - genetics Genome-Wide Association Study Humans Huntingtin Protein - genetics Huntington Disease - genetics Huntington Disease - metabolism Multifunctional Enzymes - genetics Multifunctional Enzymes - metabolism Trinucleotide Repeat Expansion - genetics Whole Exome Sequencing

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