OPRM1 and autism spectrum disorder: This appears similar with the findings of other researchers (Becker et al., 2014; Frantz et al., 2018) showing that the time of self-grooming as well as the incidences of self-grooming following social contact were increased in mice lacking the mu opioid receptor (Oprm1−/−) that recapitulate the core symptoms of autism spectrum disorders (ASD).