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Cornelia de Lange syndrome is a developmental disorder that affects many parts of the body. The features of this disorder vary widely among affected individuals and range from relatively mild to severe.
Cornelia de Lange syndrome is characterized by slow growth before and after birth, mental retardation that is usually severe to profound, abnormalities involving the arms and hands, and distinctive facial features. The facial differences include thin, arched eyebrows; long eyelashes; low-set ears; small, widely spaced teeth; and a small, upturned nose. Many affected individuals also have behavior problems similar to autism, a developmental condition that affects communication and social interaction.
Additional signs and symptoms of Cornelia de Lange syndrome can include excessive body hair (hirsutism), an unusually small head (microcephaly), hearing loss, and problems with the digestive tract. Some people with this condition are born with an opening in the roof of the mouth called a cleft palate. Seizures, heart defects, eye problems, and skeletal abnormalities also have been reported in people with this condition.
Although the exact incidence is unknown, Cornelia de Lange syndrome likely affects 1 in 10,000 to 30,000 newborns.
Mutations in the NIPBL, SMC1A, and SMC3 genes cause Cornelia de Lange syndrome.
Mutations in the NIPBL gene have been identified in about half of all cases of Cornelia de Lange syndrome. This gene provides instructions for making a protein called delangin. Although the exact function of this protein is unknown, it appears to play an essential role in directing development before birth. Delangin regulates the activity of other genes in the developing limbs, face, and other parts of the body. NIPBL mutations lead to the production of an abnormal or nonfunctional version of this protein. These changes disrupt the regulation of genes involved in normal development, leading to the varied signs and symptoms of Cornelia de Lange syndrome.
Mutations in the SMC1A gene appear to be a less common cause of Cornelia de Lange syndrome. Although individuals with mutations in this gene have many of the major features of the condition, the signs and symptoms tend to be milder than those seen with NIPBL mutations. The SMC1A gene provides instructions for making a protein that helps regulate the structure and organization of chromosomes. Like delangin, this protein probably also controls the activity of certain genes that are important for normal development. Mutations in the SMC1A gene may cause features of Cornelia de Lange syndrome by disrupting the regulation of critical genes during early development.
Rare cases of Cornelia de Lange syndrome are caused by mutations in the SMC3 gene. Like mutations in the SMC1A gene, SMC3 mutations tend to cause a relatively mild form of the condition. This gene provides instructions for making a protein that interacts with the SMC1A protein to regulate chromosome structure. Scientists are working to determine how SMC3 mutations result in the developmental problems characteristic of Cornelia de Lange syndrome.
Researchers are looking for additional changes in the NIPBL, SMC1A, and SMC3 genes, as well as mutations in other genes, that may be responsible for this condition.
When Cornelia de Lange syndrome is caused by mutations in the NIPBL or SMC3 gene, this condition is considered to have an autosomal dominant pattern of inheritance. Autosomal dominant inheritance means one copy of the altered gene in each cell is sufficient to cause the disorder. Almost all cases result from new mutations in the gene and occur in people with no history of the condition in their family.
Cases of Cornelia de Lange syndrome caused by SMC1A mutations have an X-linked pattern of inheritance. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. Studies of X-linked Cornelia de Lange syndrome indicate that one copy of the altered gene in each cell may be sufficient to cause the condition. Unlike most X-linked conditions, in which males are more frequently affected or experience more severe symptoms than females, X-linked Cornelia de Lange syndrome appears to affect males and females similarly. Most cases result from new mutations in the SMC1A gene and occur in people with no history of the condition in their family.
The CaF Directory - A description of Cornelia de Lange syndrome, its inheritance patterns and pre-natal diagnosis.
NORD - Cornelia de Lange Syndrome - Offers the synonyms, a general discussion and further resources.
Jessica's Place - About the author's daughter who has Cornelia de Lange Syndrome. Information on CdLS, updates on Jessica's progress and support links.
Cornelia de Lange Syndrome (CdLS) Foundation Outreach - Family support organization which exists to ensure the early and accurate diagnosis of CdLS, promote research into the causes and manifestations of the syndrome, and help people with a diagnosis of CdLS, and others with similar characteristics, make informed decisions throughout their lifetime.