The PMSF Medical Advisory Committee (MAC) would like to inform the patient community and the providers who care for them that around puberty or in early adulthood, some people with Phelan-McDermid syndrome are prone to developing bipolar disorder, associated psychotic features, and severe anxiety or obsessive-compulsive symptoms. Catatonia occurs in roughly 50% of Phelan-McDermid syndrome patients who develop psychiatric symptoms.