Motor signs are increasingly acknowledged as candidate transdiagnostic endophenotypic features in different clinical stages of severe mental disorders, such as schizophrenia spectrum and mood disorders.1–4 At the same time, motor signs in children and adolescents are widely recognized as proxy features of an altered neurodevelopmental trajectory associated with a higher risk of psychopathological manifestations. These motor abnormalities, spanning from developmental motor delays (eg, sitting, walking) to motor signs (eg, dyscoordination, psychomotor retardation, and psychomotor agitation), presumably reflect complex, cumulative and diachronically stratified interactions between genetic load for severe mental illness and early environmental adversities.