SNP Shot: Genomic Insights

Spondylocostal dysostosis (SCDO) refers to a group of disorders that cause abnormal bone development in the spine and ribs. This results in misshapen vertebrae that are often fused together. Scoliosis, an abnormal sideways curvature of the spine, is common in individuals with SCDO due to these vertebral malformations. Furthermore, rib bones may be fused or absent. These bone abnormalities lead to a short, rigid neck and shortened torso. Individuals with SCDO typically exhibit short-trunk dwarfism, characterized by a short body with arms and legs of normal length.

The spinal and rib abnormalities, present at birth, lead to other complications. Infants with SCDO often have small chests with limited expansion, which can cause life-threatening respiratory difficulties. As the lungs struggle to expand within the constricted chest, the diaphragm is pushed downward, causing the abdomen to protrude. This increased abdominal pressure can result in inguinal hernias, particularly in males.

Some individuals with SCDO may also have neural tube defects, birth defects that occur when the neural tube fails to close completely during early embryonic development. The neural tube is the structure that develops into the brain and spinal cord. Examples of neural tube defects associated with SCDO include spina bifida, a spinal cord abnormality, and Chiari malformation, a brain abnormality.

Although breathing problems can be fatal in infancy, many individuals with SCDO survive into adulthood.

Spondylocostal dysostosis was once grouped with spondylothoracic dysostosis under the umbrella term Jarcho-Levin syndrome. However, they are now recognized as separate conditions.

Inheritance:

Spondylocostal dysostosis can be inherited in different ways. Most types, including type 1, follow an autosomal recessive inheritance pattern. This means that both copies of the relevant gene in each cell must have mutations for the condition to develop. In these cases, both parents are carriers, each possessing one copy of the mutated gene, but typically without displaying symptoms themselves. Other forms of SCDO are inherited in an autosomal dominant manner, meaning only one copy of the altered gene is needed to cause the disorder. SCDO symptoms tend to be more severe when inherited through an autosomal recessive pattern.