PPARGC1A and Huntington disease: Previous studies have reported the presence of a common polymorphism in PPARGC1A (rs7665116) that is associated with a delay in AO of HD motor symptoms in three European HD cohorts (Che et al. 2011; Taherzadeh-Fard et al. 2009; Weydt et al. 2009), primarily contributed by patients from Italy.