Cleidocranial dysplasia is a rare skeletal dysplasia characterized by short stature, distinctive facial features and narrow, sloping shoulders caused by defective or absent collarbones (clavicles). Major symptoms may include premature closing of the soft spot on the head (coronal), delayed closure of the space between the bones of the skull (fontanels), narrow and abnormally shaped pelvic and pubic bones and deformations in the chest (thoracic region). Delayed eruption of teeth, moderately short stature, a high arched palate, a wide pelvic joint, failure of the lower jaw joints to unite, and fingers that are irregular in length may also be present. Cleidocranial dysplasia is inherited as an autosomal dominant genetic trait.
The most prominent feature of cleidocranial dysplasia is a premature closure of the two soft spots on the head (fontanels) and the fibrous joints where bones of the skull meet (sutures) causing abnormal development of the skull. Facial features typically include a prominent forehead, unusually wide face, prominent chin, small upper jaw (maxillary hypoplasia) and bulging of the skull cap. Narrow drooping shoulders caused by complete or partial absence of collarbones (clavicles) are also apparent in patients with this disorder. There may be abnormalities of the muscles in the area of the collarbones allowing for a wide range of movement of the shoulders.
Other bone abnormalities that have been found in some patients with Cleidocranial dysplasia may be: a wide pelvic joint, delayed growth of the pubic bone, a hip defect in which the thigh bone angles towards the center of the body (coxa vara), failure of the lower jaw bones to unite, a defect of the hip that causes the thigh bone to angle out to the side of the body (coxa valga), curvature of the spine (scoliosis), a small shoulder blade, and/or curvature of the upper legs so that the knees appear unusually close together (genu valgum).
Dental abnormalities may include: a delay in tooth eruption, incomplete development or absence of teeth, underdeveloped enamel and/or extra teeth. Cysts may form around the unerupted or displaced teeth in some cases. A high-arch palate or a condition in which there is a hole in the roof of the mouth (cleft palate) may be present.
Individuals with cleidocranial dysplasia have an increased risk for recurrent ear and sinus infections, upper respiratory complications and hearing loss.
Cleidocranial dysplasia is a rare disorder that is usually inherited as an autosomal dominant genetic trait. Affected individuals can show a wide range of symptoms (variable expression). Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.
The gene for cleidocranial dysplasia has been mapped to chromosome 6p21 and has been designated CBFA1.
Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 6p21″ refers to band 21 on the short arm of chromosome 6. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
Cleidocranial dysplasia is a very rare disorder that is apparent at birth and affects males and females in equal numbers. Approximately 1,000 cases of this disorder have been reported in the medical literature. The birth prevalence is approximately 1 in 1 million.
Head gear may be worn to protect the skull bones until they close. Appropriate dental care should be provided. When cleft palate is present surgery may be performed to close or block the opening. Hearing evaluations should be performed at birth and during early childhood.
Affected individuals have an increased risk for sleep apnea, sinus infections and ear infections due to delayed craniofacial development and should be monitored for these problems. Speech and language may also need to be assessed by a speech pathologist.
Genetic counseling may be of benefit for patients and their families. Other treatment is symptomatic and supportive.
The National Craniofacial Association lists several medical centers throughout the United States and Canada that specialize in treating this disorder. Contact information for this organization can be found in the Resources section of this report.
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Golan I, Baumert U, and Muessig D. Cleidocranial Dysplasia. In: The NORD Guide to Rare Disorders, Philadelphia: Lippincott, Williams and Wilkins, 2003: 182-3.
Golan I, Preising M, Wagner H, et al. A novel missense mutation of the CBFA1 gene in a family with cleidocranial dysplasia (CCD) and variable expressivity. J Craniofac Genet Dev Biol 2000;20:113-120.
Mundlos S. Cleidocranial dysplasia: clinical and molecular genetics. J Med Genet 1999;36:177-182.
Becker A, Lustmann J, Shteyer A. Cleidocranial dysplasia: part 1-general principles of the orthodontic and surgical treatment modality. Am J Orthod Dentofac Orthop 1997;11:28-33.
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McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore MD: The Johns Hopkins University Press; Entry No. 119600; Last Update: 12/7/01.