Article: Diastrophic dysplasia

Diastrophic dysplasia is a disorder of cartilage and bone development. It is inherited in a autosomal recessive pattern and affects about 1 in 100,000 births.

Affected individuals have short stature with very short arms and legs and joint problems that restrict mobility. This condition is also characterized by an inward- and downward-turning foot (called 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 called 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. Diastrophic dysplasia tends to be less severe, however.

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. The protein made by this gene 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, but in adulthood this tissue 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.

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell must be altered for a person to be affected by the disorder. Most often, the parents of a child with an autosomal recessive disorder are not affected but are carriers of one copy of the altered gene.

This article incorporates public domain text from The U.S. National Library of Medicine