FBXO32 and Huntington disease: Hdac4 up-regulation was accompanied by down-regulation its direct target Dach2 (Dachshund homolog 2) (Fig. 7B) that is a negative regulator of Myogenin. Consequently, we observed a very significant up-regulation of Myogenin (Fig. 7C) and its direct target Fbxo32 (F-box only protein 32) (Fig. 7D) in HD-related muscle atrophy.