Craniometaphyseal dysplasia, autosomal dominant
Other Names for this Disease
- Craniometaphyseal dysplasia Jackson type
What are the signs and symptoms of craniometaphyseal dysplasia?
What causes autosomal dominant craniometaphyseal dysplasia?
How is autosomal dominant craniometaphyseal dysplasia inherited?
How might craniometaphyseal dysplasia be treated?
Bone overgrowth in the head causes many of the signs and symptoms of craniometaphyseal dysplasia. Affected individuals typically have distinctive facial features such as a wide nasal bridge, a prominent forehead, wide-set eyes (hypertelorism), and a prominent jaw. Excessive new bone formation (hyperostosis) in the jaw can delay teething (dentition) or result in absent teeth. Infants with this condition may have breathing or feeding problems caused by narrow nasal passages. In severe cases, abnormal bone growth can compress the nerves that emerge from the brain and extend to various areas of the head and neck (cranial nerves). Compression of the cranial nerves can lead to paralyzed facial muscles (facial nerve palsy), blindness, or deafness.
The x-rays of individuals with craniometaphyseal dysplasia show unusually shaped long bones, particularly the large bones in the legs. The ends of these bones (metaphyses) are wider and appear less dense in people with this condition.
Autosomal dominant craniometaphyseal dysplasia is caused by mutations in the ANKH gene. The ANKH gene provides instructions for making a protein that is present in bone and transports a molecule called pyrophosphate out of cells. Pyrophosphate helps regulate bone formation by preventing mineralization, the process by which minerals such as calcium and phosphorus are deposited in developing bones. The ANKH protein may have other, unknown functions.
Mutations in the ANKH gene that cause autosomal dominant craniometaphyseal dysplasia may decrease the ANKH protein's ability to transport pyrophosphate out of cells. Reduced levels of pyrophosphate can increase bone mineralization, contributing to the bone overgrowth seen in craniometaphyseal dysplasia. Why long bones are shaped differently and only the skull bones become thicker in people with this condition remains unclear.
- Craniometaphyseal dysplasia. Genetics Home Reference (GHR). 2009; http://ghr.nlm.nih.gov/condition/craniometaphyseal-dysplasia. Accessed 8/24/2010.
- Reichenberger E, Chen IP. Craniometaphyseal Dysplasia. GeneReviews. 2007; http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=cranio-md. Accessed 8/24/2010.