[Spondylocostal dysostosis: a rare genetic disease].

Spondylocostal dysostoses represent a group of very rare genetic disorders, characterised by vertebral and costal segmentation defects, sometimes accompanied by visceral malformations. The major gene involved is DLL3, on chromosome 19. A mutation may lead to a somitogenesis defect, with segmentation defect of axial skeleton and deformations. Depending on the nature of the mutation of DLL3, spondylocostal dysostosis is transmitted as an autosomal dominant (less severe) or autosomal recessive trait (often more severe, but non lethal). Spondylocostal dysostoses must not to be confused with the Jarcho-Levin spondylothoracic dysostosis, a severe, autosomal recessive syndrome. Its most typical aspect is the crab-like appearance of the rib cage leading to major respiratory disorders. Death, due to respiratory insufficiency, usually occurs before the age of two, most often during the first few months. At this time, guidelines for treatment do not exist. We report a case of spondylocostal dysosotosis in a patient born to consanguineous turkish parents, and review the clinical and genetic data on that group of skeletal disorders.