Craniometaphyseal dysplasia is a rare condition characterized by thickening (overgrowth) of bones in the skull (cranium) and abnormalities in a region at the end of long bones known as the metaphysis. The abnormal bone growth continues throughout life. Except in the most severe cases, the lifespan of people with craniometaphyseal dysplasia is normal.

Mutations in the ANKH gene cause autosomal dominant craniometaphyseal dysplasia. The ANKH gene provides instructions for making a protein that plays a role in the development and function of cells that build bones (osteoblasts) and cells that break down bone (osteoclasts). Osteoclasts are involved in bone remodeling, a normal process in which old bone is removed and new bone is created to replace it. In addition, the ANKH protein transports a molecule called pyrophosphate out of cells. The pyrophosphate found outside of cells (extracellular pyrophosphate) helps control 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.

Craniometaphyseal dysplasia is a very rare disorder; its incidence is unknown.

When caused by mutations in the ANKH gene, craniometaphyseal dysplasia follows an autosomal dominant pattern, which means one altered copy of the ANKH gene in each cell is sufficient to cause the disorder. Individuals with autosomal dominant craniometaphyseal dysplasia typically have one parent who also has the condition. Less often, cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Published Date: June 01, 2018Published By: National Institutes of Health