What is Spondylothoracic Dysostosis?
Spondylothoracic dysostosis caused by harmful genetic changes, or mutations, in the MESP2 gene, is an inherited condition characterized by skeletal abnormalities of the back bones (vertebrae) and ribs. While mutations in the MESP2 gene typically cause spondylothoracic dysostosis, there have been very rare reports of individuals with harmful changes in the MESP2 gene that have a similar but distinct condition called spondylocostal dystosis type 2 (SCDO2).
Individuals with spondylothoracic dysostosis typically have abnormally formed vertebrae. Additionally, the vertebrae and the ribs fuse incorrectly. This results in a shortened neck and torso, a small chest, and a "crab-like" appearance of the rib cage. Affected individuals have arms and legs of normal length, but are usually shorter than average due to their shortened torso (short-trunk dwarfism). The abnormalities of the upper body can cause severe breathing complications in infants and make individuals more likely to have lung infections. Because there is not enough room in the chest, some individuals develop hernias due to the excess pressure placed on the large muscle needed for breathing (diaphragm). Individuals typically do not have any intellectual disability.
MESP2-related SCDO2 has similar features to those of spondylothoracic dysostosis, including abnormalities of the back bones (vertebrae) and ribs, but these abnormalities are thought to be less severe than those observed in spondylothoracic dysostosis. Due to the rarity of MESP2-related SCDO2, the exact characteristics are unknown.
How common is Spondylothoracic Dysostosis?
The worldwide incidence of spondylothoracic dysostosis is unknown. The condition is most common in Puerto Rico, where 1 in 12,000 individuals are affected. MESP2-related SCDO2 is extremely rare, with only a few cases reported.
How is Spondylothoracic Dysostosis treated?
There is currently no cure for spondylothoracic dysostosis, and treatment focuses on symptoms as they arise. Infants usually require mechanical help to breathe. Surgery may be required to repair hernias and bone malformations. Lung function, heart function, and growth and development are closely monitored by physicians throughout an affected individuals' life.
What is the prognosis for an individual with Spondylothoracic Dysostosis?
The prognosis for an individual with spondylothoracic dysostosis is poor. Approximately half of all individuals die in infancy from respiratory failure. Of those who survive infancy, prognosis is good, with minimal medical complications and normal intelligence.