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Campomelic dysplasia is a genetic disorder that affects the development of the skeleton and reproductive system. This condition is often life-threatening in the newborn period because of respiratory problems. Affected children are typically born with bowing of the long bones in the legs and may also have bowing in the arms. About 75% of the children have external genitalia that do not look clearly male or clearly female (ambiguous genitalia). Common findings include distinctive facial features (including a small chin, prominent eyes, flat face, and a large head compared to their body size); a particular group of physical features, called Pierre-Robin sequence; short legs; dislocated hips; underdeveloped shoulder blades; bone abnormalities in the neck; and feet that are abnormally rotated (club feet). It is caused by mutations in the SOX9 gene and is inherited in an autosomal dominant pattern, although most cases result from a new mutation in the person with the genetic disorder. Treatment typically includes multiple surgeries to correct some of the abnormalities present.
Bowing of the limbs, the feature that gave the disorder its name (campomelic is derived from the Greek for “bent limb), does not have to be present. When the limbs are not bowed, the term “acampomelic campomelic dysplasia” is used.
Source: GARD Last updated on 05-01-20
The signs and symptoms may include:
People who survive childhood may develop an abnormal curvature of the spine (scoliosis) and other spine abnormalities such as anomalies of the neck bones, which compress the spinal cord, as they age. People with campomelic dysplasia may also have short stature and hearing loss.
Some people with features of this genetic disorder may not have bowed limbs and are said to have acampomelic campomelic dysplasia.
Last updated on 05-01-20
Campomelic dysplasia is inherited in an autosomal dominant pattern, which means that one copy of the altered (mutated) gene in each cell is enough to cause the disorder. If a person has an autosomal dominant genetic disorder, with each pregnancy, there is a 50% (1 in 2) chance for the embryo to have the genetic disorder, and a 50% chance for the embryo to not have the genetic disorder. It should be noted that this risk is for each separate pregnancy; it does not mean that 50% of an individual's pregnancies will be affected by the genetic disorder.
Most cases of campomelic dysplasia result from new ( de novo ) mutations in or near the SOX9 gene and occur in people with no history of the genetic disorder in their family. Rarely, people with campomelic dysplasia inherit a chromosome abnormality (such as a deletion, de novo translocation, or inversion) near or involving the SOX9 gene from a parent who may or may not show mild signs and symptoms of campomelic dysplasia.
Because most people with campomelic dysplasia have the disorder as the result of a de novo mutation, parents of these people usually do not have signs and symptoms of the genetic disorder. However, a few adults have been diagnosed with campomelic dysplasia after the birth of an affected child or the diagnosis of a fetus during pregnancy.
Recurrence in siblings has occurred, and mosaicism has been reported. Mosaicism is when a person has two or more cell lines with different genetic or chromosomal make-ups. A person may have some cells with the mutation and some cells without (including egg or sperm cells) and not have any signs or symptoms of the genetic disorder. If some egg or sperm cells carry the mutation or chromosome abnormality, the genetic disorder can be inherited by that person's children. Familial translocations (when a whole chromosome or segment of a chromosome becomes attached to or interchanged with another whole chromosome or segment) involving the SOX9 gene have been reported but are rare.
The risk to siblings of a person with campomelic dysplasia depends on the genetic status of the affected person's parents. If a non-mosaic parent of the affected individual has signs and symptoms of the condition, the risk to the siblings is 50%. Because parental mosaicism has been reported, the siblings of a person with the genetic disorder are at an estimated 2%-5% risk, even if the disease-causing mutation found in the person with campomelic disorder cannot be detected in either parent.
The risk to a child of a parent with a non-mosaic SOX9 gene mutation is 50% (1 in 2). If the parent has a chromosome rearrangement involving SOX9 , the risk would depend on the specific chromosome abnormality.
Because of the complexity of the inheritance of campomelic dysplasia, we recommend speaking with a genetics professional.
Last updated on 05-01-20
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