120). We described before how ATXN3 contributes to the DDR. Although no hypersensitivity to DNA-damaging agents has been reported in SCA3 patients, there is an impact of the ATXN3-PolyQ version in DNA repair, observed as a dramatic increase in focus formation of phosphorylated H2AX and 53BP1 in cells expressing ATXN3-PolyQ, SCA3 mouse brains and brain sections from SCA3 patients, indicating an accumulation of DNA damage (Refs 67, 140). Here, ATXN3 is linked to Spinocerebellar ataxia type 3.