TCF4 and schizophrenia: The clinical picture of children with autistic features and developmental delay is partly similar to that of schizophrenia with leading negative symptoms and severe neurocognitive deficit; neuroimaging studies show an increased volume of the cerebral ventricles in children with Pitt–Hopkins syndrome [28], so the contribution of polymorphic variants of the TCF4 gene to the formation of independent clinical, cognitive, and neuroimaging phenotypes appears systemic.