What is Escobar Syndrome?
Escobar syndrome, or multiple pterygium syndrome, is an autosomal recessive disorder present at birth (congenital). An autosomal recessive disorder means two copies of abnormally mutated genes - one from each parent - are present for the trait or disease to develop.
Escobar syndrome is a collection of disorders referred to as multiple pterygium syndromes. These disorders are mainly characterized by arthrogryposis (joint contractures) and pterygia (webbing) of the neck and large joints. The condition commonly occurs in children from consanguineous relationships: relationships of two people closely related. Escobar syndrome is a form of arthrogryposis multiplex congenita.
Causes of Escobar Syndrome
Escobar syndrome is a rare genetic disorder caused by mutations or changes in the CHRNG gene (OMIM 100730), on chromosome 2q. This gene encodes the gamma subunit of the acetylcholine receptor (AChR), which is noted in the fetus until around 33 weeks gestation, when it is replaced by another subunit to form the adult AChR protein. The severity of the CHRNG gene mutation influences the severity of the condition, and the complete absence of the gamma subunit will result in lethal multiple pterygium syndrome (OMIM 253290), a more serious form of Escobar syndrome.
Signs and Symptoms of Escobar Syndrome
Signs and symptoms of Escobar syndrome include:
- Joint contractures
- Pterygia of the neck, fingers, forearms, inner thighs, and backs of the knee
- Respiratory distress
- Short stature
- Craniofacial dysmorphism
- Ptosis (drooping eyelids)
- Facial weakness
- Scoliosis
- Pneumonia
- Cleft palate
- Clubfeet
- Micrognathia (small jaw)
- Downward-slanting eyes
- Decreased movements
- Vertebral deformities
Diagnosis of Escobar Syndrome
CHRNG is the only gene known to be associated with Escobar syndrome. Hence, genetic testing is the mainstay for diagnosing this condition. A blood sample is obtained for genetic testing to detect point mutations, small deletions, and small insertions in the genes, which can confirm the diagnosis of Escobar syndrome. Parents’ medical history and family history are also reviewed for additional details.
Treatment for Escobar Syndrome
Currently, there is no cure for Escobar syndrome. As a result, treatment is aimed at managing symptoms through a multi-disciplinary approach.
Orthopedics must be involved for problems arising from vertebral abnormalities and scoliosis. Respiratory infections should be treated promptly as affected infants have a high chance of developing pneumonia due to a small rib cage. Involvement of plastic surgery may benefit infants with webbing in the extremities, neck, and longer joints. Physical therapy is crucial to help minimize contractures, improve range of motion of affected joints, and strengthen muscles to prevent atrophy. When ptosis is noted in a child, ophthalmology must be involved for optimal treatment management. Children should also be assessed by an audiologist, as there is a high risk of developing conductive hearing loss. Surgery may be employed to transfer tendons or reposition bones in order to improve muscle function and correct limb contractures, clubfeet, hip dislocations, or other limb deformities that limit or interfere with overall function.
