Deletion of the MAO-A and MAO-B genes are not lethal but Norrie disease patients with MAO-A and MAO-B gene deletions show severe intellectual disability, growth failure, alteration of sleep patterns, autistic-like symptoms, and bilateral congenital blindness (Bortolato et al., 2018; Rodriguez-Munoz et al., 2018). Here, MAOA is linked to Norrie disease.