Campomelic dysplasia (CMD) is a rare genetic disorder that affects the development of the skeleton and reproductive system
Campomelic dysplasia (CMD) is a rare genetic disorder that affects the development of the skeleton and reproductive system. People affected by this condition are typically born with bowing of the long bones in the legs, along with other bone abnormalities.
While the severity of the disease varies by individual, most babies with campomelic dysplasia don’t survive past 4 weeks due to problems with the respiratory system.
What are signs and symptoms of campomelic dysplasia?
Along with bowing and irregular shaping of the lower limbs, campomelic dysplasia is also characterized by incomplete development of external genitalia.
About 75% of people with the condition with a typical male chromosome pattern (46, XY) have ambiguous genitalia or normal female genitalia, where the internal reproductive organs don’t correspond with the external genitalia. For example, an individual with external female genitalia may have either two testes or one testis and one ovary.
Other signs and symptoms of the condition include:
- Underdeveloped shoulder blades
- Shortened lower limbs
- Vertically oriented and narrow pelvis
- Enlarged head
- Small lower jaw
- Small chin
- Prominent eyes
- Cleft palate (an opening or split in the roof of the mouth)
- Flat nasal bridge
- Low set ears
- Clubfeet (a birth defect where one or both feet are rotated inward and downward)
- Dislocated hips
- 11 pairs of ribs instead of 12
- Bone abnormalities in the neck and spine
Babies who survive into adulthood develop an abnormal curvature of the spine (scoliosis) as they age. Some may even develop short stature and suffer from hearing loss.
What causes campomelic dysplasia?
Campomelic dysplasia is caused by genetic mutations in or near the SOX9 gene. This gene is involved in the regulation of SOX9 protein, which controls the development of the skeletal system, reproductive system and other systems of the body.
Mutations in this gene lead to abnormal development of these structures and cause the signs and symptoms of campomelic dysplasia.
How is campomelic dysplasia diagnosed?
If a doctor suspects campomelic dysplasia after physical examination, they may order additional tests to confirm the diagnosis:
- X-rays of vertebrae, hips, chest, legs and feet
- Ultrasound of the abdomen
- Echocardiogram of the heart
- DNA analysis of blood (confirmatory blood test to detect mutations in the SOX9 gene)
How is campomelic dysplasia treated?
There is no cure for campomelic dysplasia, and treatment is aimed at preventing or managing symptoms. Surgical procedures may also help in correcting the structural abnormalities. Treatment may include the following:
- Mechanical breathing assistance, such as positive end-expiratory pressure (PEEP), may help affected individuals with respiratory problems.
- Bone surgery may help alleviate some of the more serious bone deformities. Bowed legs usually straighten by themselves
In 2004, the vertical expandable prosthetic titanium rib (VEPTR) was approved by the FDA as a treatment for thoracic insufficiency syndrome (TIS) in children affected with campomelic dysplasia. TIS is a congenital condition where severe deformities in the ribs, chest and spine restrict movement of the lungs and prevent normal breathing. The VEPTR is implanted in the chest to help straighten the spine and separate the ribs, allowing adequate expansion of the lungs and easier breathing as a result.