Sacsin has five domains: ubiquitin-like domain (Ubl), three large sacsin internal repeats (SIRPT1, SIRPT2, SIRPT3), xeroderma pigmentosum C-binding domain (XPCB), J-domain (DNAJ) and higher eukaryotes and prokaryotes nucleotide-binding (HEPN) domain. The gene discussed is SACS; the disease is xeroderma pigmentosum.