FAN1 and Huntington disease: Similar to MSH3, variation in FAN1 (rs3512) has also been implicated in somaticinstability52 and has been previously shown to predict delayed age of onset in Huntington’s disease.26,36FAN1 overexpression reduces CAG repeat expansion in human cell modes54; however, in our study, there was no significant effect of rs2140734 (or rs3512) on cognitive function.