Cornelia de Lange syndrome (CdLS) is a rare genetic disorder that is apparent at birth (congenital). Associated symptoms and findings typically include delays in physical development before and after birth (prenatal and postnatal growth retardation); characteristic abnormalities of the head and facial (craniofacial) area, resulting in a distinctive facial appearance; malformations of the hands and arms (upper limbs); and mild to severe mental retardation. Many infants and children with the disorder have an unusually small, short head (microbrachycephaly); an abnormally long vertical groove between the upper lip and nose (philtrum); a depressed nasal bridge; upturned nostrils (anteverted nares); and a protruding upper jaw (maxillary prognathism). Additional, characteristic facial abnormalities may include thin, downturned lips; low-set ears; arched, well-defined eyebrows that grow together across the base of the nose (synophrys); an unusually low hairline on the forehead and the back of the neck; and abnormally curly, long eyelashes. Affected individuals may also have distinctive malformations of the limbs, such as unusually small hands and feet, inward deviation (clinodactyly) of the fifth fingers, or webbing (syndactyly) of certain toes. Less commonly, there may be absence of the forearms, hands, and fingers. Infants with Cornelia de Lange syndrome may also have feeding and breathing difficulties; an increased susceptibility to respiratory infections; a low-pitched "growling" cry; heart defects; delayed skeletal maturation; hearing loss; or other physical abnormalities. The range and severity of associated symptoms and findings may be extremely variable from case to case.

Cornelia de Lange syndrome can be inherited as an autosomal dominant condition or an X-linked condition. The only genes that have been found to be associated with Cornelia de Lange syndrome are the NIPBL gene on chromosome 5 and the SMC1L1 gene on the X chromosome. Most affected individuals have an abnormal gene as a result of a new gene mutation and do not have an affected parent. Other genes may be found to be associated with Cornelia de Lange syndrome in the future.

This developmental disorder affects many parts of the body. The severity of the condition and the associated signs and symptoms can vary widely but may include distinctive facial characteristics, growth delays, Intellectual disability and limb defects. 

CdLS can be inherited in an autosomal dominant (NIPBL, SMC2, or RAD21) or X-linked (SMC1A or HDAC8) manner. However, most cases result from new (de novo) genetic changes and occur in people with no family history of the condition.

The treatment of CdLS is directed toward the specific symptoms that are apparent in each individual. Treatment may require the efforts of a team of specialists working together to systematically and comprehensively plan an affected child’s treatment. Such specialists may include pediatricians; geneticists; surgeons; specialists who diagnose and treat skeletal disorders (orthopedists); plastic surgeons; orthopedic surgeons; specialists who diagnose and treat abnormalities of the digestive system (gastroenterologists), feeding specialists, disorders of the urinary tract (urologists), and abnormalities of the ears, nose, and throat (otolaryngologists); pediatric heart specialists (cardiologists); dental specialists; speech pathologists; specialists who assess and treat hearing problems (audiologists); eye specialists; physical and occupational therapists; and/or other health care professionals.

Affected infants and children may be closely monitored for certain abnormalities potentially associated with CdLS (e.g., potential intestinal obstruction due to gastrointestinal abnormalities, cardiac defects, gastroesophageal reflux, glue ear, and/or susceptibility to respiratory infections) to ensure early detection and prompt treatment.

Specific therapies for the treatment of CdLS are symptomatic and supportive. In some children, surgery may be performed to help correct cleft palate, cardiac defects and/or diaphragmatic hernias. Plastic surgery may be helpful in reducing excessive hair. Some gastrointestinal, genitourinary, and/or cardiac malformations may be treated with certain medications, surgical intervention, and/or other techniques. The surgical procedures performed will depend upon the location and severity of the anatomical abnormalities and their associated symptoms. Respiratory infections may be treated with antibiotic drug therapy and/or other medications that may help fight infection.

Various orthopedic techniques may be used to help treat limb deformities. Hearing aids may be beneficial in some children. Treatment with anticonvulsant medications may help prevent, reduce, or control seizures in some affected children.

Early intervention is important in ensuring that children with CdLS reach their highest potential. Services that may be beneficial include special remedial education, vocational training, speech therapy, and/or other medical and/or social services.

Genetic counseling is recommended for affected individuals and their families. Other treatment is symptomatic and supportive.