Diastrophic Dysplasia

What is diastrophic dysplasia?

Diastrophic dysplasia is a rare disorder that affects the normal development of cartilage and bone. It’s congenital, meaning a person is born with it.

The condition results in:

• Joint dysplasia, abnormal development of joints.
• Short arms and legs.
• Short stature (height).
• Skeletal dysplasia (abnormal development of bones).

It usually affects the following body parts:

• Ears.
• Face.
• Feet.
• Hands.
• Hips.
• Legs.
• Spine.

Diastrophic dysplasia is also called:

• DD or DTD.
• Diastrophic dwarfism.
• Diastrophic nanism syndrome.
• Short-limbed dwarfism.

How rare is diastrophic dysplasia?

Diastrophic dysplasia is rare, estimated to affect 1 in 500,000 newborns. The disorder is more common in Finland, probably because of shared ancestry. There, it affects about 1 in 30,000 babies.

What causes diastrophic dysplasia?

Diastrophic dysplasia is caused by a genetic mutation. It’s hereditary, which means it can be passed down in families.

The mutation affects a gene that’s important to the development of cartilage. Cartilage is a tough but flexible tissue that forms a fetus’ skeleton in the early stages of human development.

Most cartilage turns to bone as a baby develops, except for a few areas (ends of bones, nose and ears). But when this mutation occurs, the gene cannot properly contribute to the formation of cartilage and bones.

What gene is mutated in diastrophic dysplasia?

The specific gene mutation that causes DTD occurs in the SLC26A2 gene. It’s also called DTDST (diastrophic dysplasia sulfate transporter). The gene is responsible for making a protein important in making cartilage, as well as changing cartilage to bone.

A person can be a carrier of the genetic mutation but not have the disorder. If a baby’s mother and father are both carriers, a baby has a 25% chance of developing the disorder.

What are the symptoms of diastrophic dysplasia?

Symptoms of diastrophic dwarfism vary widely. Most people with the disorder have short stature and failure to grow. But other symptoms may occur throughout the body, such as:

Head and mouth

• Broad forehead with a high hairline.
• Thick, swollen or deformed ears.
• Abnormally small jaw (micrognathia).
• Dental abnormalities, such as small teeth or dental crowding.
• Cleft palate, an abnormal opening in the roof of the mouth.
• Breathing problems.

Extremities

• Brachydactyly, abnormally short fingers.
• “Hitchhiker’s thumbs,” which point outward.
• Clubfoot, when one foot or both feet turn inward.
• Short, bowed arms and legs.

Joints

• Contractures, joint deformities that can stop joints from fully extending, limiting movement.
• Fused joints that don’t bend, which can restrict movement.
• Loose or stiff joints, or joint dislocations.
• Osteoarthritis with joint pain.

Spine

• Kyphosis, excessive curvature of the spine, creating the appearance of a hunch or rounded back.
• Scoliosis, side-to-side curvature of your spine.

Does diastrophic dysplasia affect brain development?

Diastrophic dysplasia is not known to affect the brain or brain development. People with DTD have normal intelligence.

How is diastrophic dysplasia diagnosed?

Sometimes diastrophic dwarfism can be detected before an affected baby is born. If your family has a history of the disorder, your healthcare team may recommend genetic testing early in pregnancy.

The condition also may be revealed by fetal ultrasonography. This test provides pictures of a baby as it develops in the womb. If the images show shortened or deformed bones, the healthcare provider might recommend genetic testing for diastrophic dysplasia.

But the condition usually is identified when a baby is born. The diagnosis is based on physical examination and imaging tests that show deformed or shortened bones.

What is the treatment for diastrophic dysplasia?

There’s no cure for DTD. Treatment aims to manage the symptoms an individual develops and support health and wellness as much as possible.

A person with the disorder may need a team of specialists, including:

• Audiologist, who treats hearing problems.
• Genetic counselor to help the family understand the condition.
• Nutritionists can help with food intake when there are problems with your mouth and eating.
• Orthodontist, who fixes issues with the teeth and jaw.
• Orthopaedist, who specializes in bone and joint problems.
• Pediatrician, a specialist who treats children.
• Physical therapists and occupational therapists to help people learn to move and function as well as possible.
• A pulmonologist, who specializes in helping people manage breathing issues.
• Surgeons to correct deformities as needed.

How can I reduce the risk of diastrophic dysplasia?

There’s no way to prevent diastrophic dwarfism. If someone in your family has the disorder, consider talking to your healthcare provider about genetic testing before pregnancy. Testing and counseling can help determine whether you are a carrier and what it means for your family.

What’s the outlook for people with diastrophic dysplasia?

Diastrophic dysplasia can be fatal in newborns with respiratory complications, but most people live into adulthood. They often must live with some pain and disability, depending on the severity of the disorder.

What questions can I ask my child’s healthcare provider?

If your child has diastrophic dysplasia, consider asking the following questions to get more information:

• What body parts are affected?
• Will this be life-limiting?
• What specialists should my child see, and how often?
• Can we do anything to manage bone or joint pain?
• Do you know of any support groups for people with this condition or similar disorders?
• If I have other children, will they have this condition, too?

A note from Cleveland Clinic

Diastrophic dysplasia is a rare congenital disorder that affects the normal development of cartilage and bone. People with the condition often have short stature, short arms and legs, and problems with their joints. If your family has a history of diastrophic dysplasia, consider talking to your healthcare provider about genetic testing and counseling.