APTX and nervous system disorder: An increasing number of evidence in defective BER pathway machinery have been linked to various neurological diseases; for instance, spinocerebellar ataxia with axonal neuropathy-1 (SCAN1) and ataxia-oculomotor apraxia-1 (AOA1) are caused by mutations in two peripheral SSBR proteins AOA1 and tyrosyl-DNA phosphodiesterase 1 (TDP-1), clearly showing the importance of BER in human neuronal maintenance (El-Khamisy et al., 2005; Ahel et al., 2006).