For example, POLγA mutations in the spacer domain, such as p.W748S, have been found to be a significant cause of inherited neurodegenerative phenotypes, like ataxia, parkinsonism, and seizures (Van Goethem et al., 2003; Luoma et al., 2004; Hakonen et al., 2005). Here, POLG is linked to Ataxia.