HDAC4 binds to mutant HTT in a polyglutamine length-dependent manner and is localized to the cytoplasmic inclusions in striatal neurons in HD mouse models, and genetic reduction of murine Hdac4 reduces cytoplasmic mutant Htt aggregation and restores cortico-striatal synaptic transmission in HdhQ150 KI mice44. Here, HTT is linked to Huntington disease.