Previous studies have described changes in SMADs and upstream components of the TGF‐β signaling pathway in cellular and mouse models of HD, as well as in blood from HD cases versus controls, but the direction of these effects was contradictory between studies (Battaglia et al, 2011; Ring et al, 2015; Bowles et al, 2017). This evidence concerns the gene TGFB1 and Huntington disease.