Diastrophic Dysplasia

What is diastrophic dysplasia?

Diastrophic dysplasia is a disorder of cartilage and bone development. Affected individuals have short stature with very short arms and legs and joint problems that restrict mobility. This condition is also characterised by an inward- and downward-turning foot (a clubfoot), progressive curvature of the spine, and unusually positioned thumbs (hitchhiker thumbs). About half of infants with diastrophic dysplasia are born with an opening in the roof of the mouth (a cleft palate). Swelling of the external ears is also common in newborns and can lead to thickened, deformed ears.

The signs and symptoms of diastrophic dysplasia are similar to those of another skeletal disorder called atelosteogenesis, type 2; however, diastrophic dysplasia tends to be less severe.

How common is diastrophic dysplasia?

Although the exact incidence of this condition is unknown, researchers estimate that it affects about 1 in 100,000 newborns. Diastrophic dysplasia occurs in all populations, but appears to be particularly common in Finland.

What genes are related to diastrophic dysplasia?

Mutations in the SLC26A2 gene cause diastrophic dysplasia.

Diastrophic dysplasia is one of a spectrum of skeletal disorders caused by mutations in the SLC26A2 gene. This gene provides instructions for making a protein that is essential for the normal development of cartilage and for its conversion to bone. Cartilage is a tough, flexible tissue that makes up much of the skeleton during early development. Most cartilage is later converted to bone, except for the cartilage that continues to cover and protect the ends of bones and is present in the nose and external ears. Mutations in the SLC26A2 gene alter the structure of developing cartilage, preventing bones from forming properly and resulting in the skeletal problems characteristic of diastrophic dysplasia.

How do people inherit diastrophic dysplasia?

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

What other names do people use for diastrophic dysplasia?

• Diastrophic dwarfism
• DTD