Despite the substantial alterations to the auditory brainstem in FXS, it has never been clearly shown, beyond patient report and surveys, that mice or humans with a mutation in Fmr1 have impairments in their ability to localize sound in normal listening or complex acoustic environments (Baranek et al., 2002, 2008; Rogers et al., 2003). The gene discussed is FMR1; the disease is fragile X syndrome.