Cornelia de Lange syndrome is characterized by growth retardation of prenatal onset, microcephaly, small hands and feet, limb abnormalities, and reflux. Dysmorphic features include synophrys, upturned nose, downturned mouth, and low-set ears. Long eyelashes are common as are hirsuitism and a coarsened appearance. Cleft palate, kidney abnormalities, and heart defects are present in some patients. Intellectual disability is common, and many individuals with Cornelia de Lange also experience hearing loss. Other issues may include self-injurious behaviors, obsessive-compulsive disorder, and autistic tendencies. Cornelia de Lange syndrome often results from de novo autosomal dominant mutations in NIPBL, RAD21, or SMC3, while SMC1A and HDAC8 demonstrate X-linked inheritance with both males and females exhibiting symptoms. Cornelia de Lange shows variable expressivity although individuals with NIPBL mutations tend to show more severe phenotypes.