HTT and neurodegenerative disease: Recent studies have revealed that some neurodegenerative disease proteins, such as androgen receptor (AR) [25], huntingtin [26], ataxin-1 [27], ataxin-7 [28], DJ-1 [35], tau [36], and a-synuclein [36], are also modified by SUMOs, implying that SUMOylation of these disease-related proteins may participate in the regulation of their functions and thereby be associated with their pathogenic role.