Autosomal recessive spondylocostal dysostosis

Autosomal recessive spondylocostal dysostosis (SCDO) is a group of rare genetic skeletal disorders characterized by multiple vertebral segmentation defects and rib anomalies. The condition is also known as jarcho-Levin syndrome (though this term has been used more broadly), and specific subtypes include SCDO types 1 through 6, caused by mutations in genes involved in the Notch signaling pathway, including DLL3 (SCDO1), MESP2 (SCDO2), LFNG (SCDO3), HES7 (SCDO4), TBX6 (SCDO5), and RIPPLY2 (SCDO6). These genes play critical roles in somitogenesis — the embryonic process that forms the vertebrae and ribs. The hallmark features of autosomal recessive SCDO include multiple contiguous vertebral segmentation abnormalities (hemivertebrae, butterfly vertebrae, vertebral fusions, and bars) along with malaligned and fused ribs. This results in a shortened trunk with a disproportionately short stature, while limb length is typically normal. The rib abnormalities can lead to a small, rigid thorax, which may cause restrictive lung disease and respiratory insufficiency, particularly in the neonatal period and infancy. Affected individuals may also develop scoliosis or kyphoscoliosis that can worsen with growth. The condition is typically apparent at birth or prenatally on ultrasound. There is currently no cure for autosomal recessive spondylocostal dysostosis. Treatment is supportive and multidisciplinary, focusing on managing respiratory complications, which are the primary source of morbidity and mortality, especially in infancy. Respiratory support, including mechanical ventilation in severe cases, may be necessary. Orthopedic management of progressive scoliosis may include bracing or surgical intervention such as growing rod techniques. With appropriate respiratory care, many individuals survive into adulthood. Genetic counseling is recommended for affected families, and prenatal diagnosis is possible when the causative mutation is known.

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