CELF4 haploinsufficiency is responsible for the phenotype associated with del (18q) syndrome that is characterized by neurodevelopmental disorder including febrile seizures/epilepsy, clumsiness, intellectual disability of variable degree, autism spectrum disorder, autism features and/or behavioral disturbances such as impulsiveness, restless and anxiety disorder. All patients with molecularly defined CELF4 haploinsufficiency had autism or autistic traits despite differing degrees of intellectual disability. Patients may have some facial dysmorphism as prominent forehead, deeply set eyes, small midface, smooth philtrum and thin lips. Eye abnormalities especially high-degree myopia may be present. Obesity caused by uninhibited eating behavior is part of the clinical spectrum.
