What is diastrophic dysplasia?
Diastrophic dysplasia is a rare congenital dwarfism
disorder that is characterized by a short stature and unusually short arms and legs, abnormal bone and joint development, especially in the hands and feet, and other malformations in the craniofacial area.
Notably, diastrophic dysplasia is particularly frequent in Finland and people of Finnish descent.
What causes diastrophic dysplasia?
During normal embryonic and fetal development, cartilage in many parts of the body is replaced by bone, which allows the long bones in particular to grow. However, in diastrophic dysplasia, this process (called ossification) is delayed, causing the features of diastrophic dysplasia.
Mutations in the DTDST gene on the long arm of chromosome 5 are responsible for this delayed ossification, as they result in abnormalities of the cartilage cells and the substance between these cells in the body.
The DTDST mutations are inherited in an autosomal recessive inheritance pattern.
What are the symptoms of diastrophic dysplasia?
The signs and symptoms of diastrophic dysplasia are extremely variable, but all cases have some kind of abnormal development of the bones and joints of the body. These abnormalities can include the following:
- Lack of a “growth spurt” during puberty
- Markedly short, bowed arms and legs
- Short stature
- “Hitchhiker thumbs” that deviate away from the body or fused finger joints that cause limited flexion and reduced mobility of the fingers
- Foot deformities, such as clubfoot, flexed feet, or deviated heels or toes
- Partial dislocation of particular joints of the body
- Scoliosis or kyphosis (curvatures of the spine)
- Cysts in the outer visible portions of the ears that cause swelling and inflammation
It is also common for individuals with diastrophic dysplasia to develop craniofacial malformations, such as an unusually high, prominent forehead, abnormally small jaws, and cleft palate.
How is diastrophic dysplasia diagnosed?
If families have a previous history of diastrophic dysplasia, the disorder may be detected prenatally, as early as the first trimester, using DNA marker testing, or during the second trimester through a fetal ultrasonography.
However, in most cases, diastrophic dysplasia is diagnosed and/or confirmed at birth based on a thorough clinical evaluation and an identification of the characteristic physical findings of the disease. Specialized testing, such as CT scans, MRI scans, and audiological tests, can also be conducted to then detect and confirm the features of diastrophic dysplasia.
What are the available treatments for diastrophic dysplasia?
Unfortunately, there is no cure for diastrophic dysplasia, so treatment is symptomatic and supportive. Preventative treatment for respiratory obstruction, which often occurs from the symptoms of the disorder, should be administered. Surgical procedures can help correct any malformations that result from breathing and/or feeding difficulties.
In addition to these, orthopedic techniques, including corrective surgery and physical therapy, are often used to help prevent and correct the skeletal deformities that are associated with diastrophic dysplasia.
Where can I find more information on diastrophic dysplasia?