To date, deleterious variants in TCF20 have been identified in cohorts of individuals with diverse neurodevelopmental disorders (NDDs) including ID (66%, n = 8/12), language delay (42%, n = 5/12), neurobehavioral abnormalities (58%, n = 7/12), hypotonia (25%, n = 3/12), one patient with seizures (n = 1/12, 8%), and macrocephaly/overgrowth (25%, n = 3/12) [14–16] (Tables 1, 2, and 3). The gene discussed is TCF20; the disease is neurodevelopmental disorder.