DAO and schizophrenia: Here, the R199W mutation in DAAO, yielding a loss of enzymatic activity, has been associated with a familial case of amyotrophic lateral sclerosis (Mitchell et al., 2010) and association studies have linked DAAO (as well as its main modulatory partner pLG72) with schizophrenia susceptibility; (for a review, see Sacchi et al., 2012, 2016).