Spondylothoracic dysostosis (STD) is an inherited condition characterized by skeletal abnormalities of the vertebrae and ribs. For patients with STD, their bones do not form properly resulting in fusion of the ribs to the vertebrae, giving a fan-like appearance. This fusion results in a shortened neck and torso and a small chest. These abnormalities of the upper-body can cause significant breathing complications as the chest in unable to expand correctly. This can be life-threatening. Affected patients have normal length arms and legs, but due to the shortened torso, have short stature. Many patients with STD develop hernias due to the excess pressure placed on the diaphragm when breathing.
Mutations in the MESP1 gene cause STD and can also cause a related, but thought to be distinct condition, called spondylocostal dystosis type 2 (SCDO2). SCDO2 is thought to be milder than STD, but also more rare. Due to the rarity of SCDO2 the exact characteristics are unknown.
Spondylothoracic dysostosis affects approximately 1 in 200,000 people worldwide. The condition is more common in Puerto Rico where 1/12,000 people are affected.
There is no cure for STD, and treatment focuses on symptoms as they arise. Infants usually require mechanical help to breathe. Hernias are repaired as necessary. Respiratory and cardiac function, as well as growth and development, are monitored by physicians.
Generally the prognosis for a person with STD is poor. Approximately half of all patients die in infancy from respiratory failure. Of those who survive infancy, prognosis is good with minimal medical complications and normal intelligence.
Explanations of an extensive number of genetic diseases written for everyday people by the U.S. government's National Institutes of Health.
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