CTNNB1 and severe intellectual disability-progressive spastic diplegia syndrome: In a significant scientific effort to understand the link between genetics and symptoms in CTNNB1 syndrome, an observational study including 125 CTNNB1 patients from all over the world has been completed (NCT04812119).26 Its main goal was to interview parents or legal guardians of patients with confirmed CTNNB1 diagnosis and assess them on an extensive questionnaire covering various aspects of the patient’s history, including prenatal and delivery risk factors, current medical issues, and standardized questionnaires on different areas of development and behavior.