APTX and Ataxia: It is unclear why ATM deficiency causes ataxia, but it is far from the only DDR protein linked to ataxia, as Aprataxin (APTX) (Aicardi et al., 1988), Meiotic recombination 11 homolog 1 (MRE11) (Sedghi et al., 2018), Nibrin (NBS1) (van der Burgt et al., 1996), Senataxin (SETX) (Moreira et al., 2004), and Tyrosyl-DNA Phosphodiesterase 1 (TDP1) (Takashima et al., 2002) when absent or dysfunctional can cause cerebellar-related ataxia.