There are five sub-families of DUBs classified by their sequence diversity: the ubiquitin C-terminal hydrolases (UCHs), the ubiquitin-specific peptidases (USPs/UBPs), the ovarian tumor (OTU) domain proteins, the Josephin or Machado-Joseph disease (MJD) proteins, and the JAMM (Jab1/MPN domain-associated metalloisopeptidase) domain proteins. Here, ATXN3 is linked to Machado-Joseph disease.