SPONDYLOCOSTAL DYSOSTOSIS

QUESTIONS AND ANSWERS.

All the Information you Need to Know about Spondylocostal Dysostosis (SCDO)

A short, inflexible neck, protruding belly, and mild, non-progressive scoliosis are common features of SCDO patients. The compressed trunk appears abnormally short in relation to the person’s entire height. The restrictions imposed by rib cage deformation affect lung development, and signs and symptoms like tachypnea, fatigue, or lung infections are frequently present as a result of pulmonary hypoplasia and abnormal chest compliance. Respiratory complications appear as one of the most frequent causes of morbidity and mortality in affected individuals. The anomalies in SCDO are often isolated and limited to the spine and ribs.

Spondylothoracic Dysostosis (STD) is a condition that is substantially comparable, although it is more severe and clinically and radiologically different. The primary characteristic of STD appears as a shortened, symmetrical chest, fused thoracic vertebrae, and generally normal ribs that develop a fan or crab-like form when united close to their spinal origin. Early mortality due to infection or dysfunctional breathing appears medically linked to STDs.

The doctors examination, the radiological scans and our genetic testing laboratory serve as the foundation for the SCDO diagnosis. The radiological findings are varied and include the involvement of several spinal segments, particularly in the thoracic region, which exhibit butterfly-shaped vertebrae, fused hemivertebrae, or vertebrae, as well as various abnormalities in rib morphology. These can result in asymmetries with improper rib alignment and frequently a decrease in the overall number of ribs. They include rib growth, fusion, bifurcation, or even agenesis. 

Causes

Spondylocostal Dysostosis has been linked to mutations in numerous genes. Mutations in the DLL3 gene are what lead to this condition’s type 1, the most prevalent version of the disorder. A tiny proportion of instances of the syndrome are due to mutations in the other known genes. The DLL3 gene, along with other Spondylocostal Dysostosis-related genes, functions in the Notch signaling pathway, a crucial one in embryonic development. During early development, a process known as somite segmentation is one of the roles of Notch signaling in controlling the separation of ribs and future vertebrae from one another.

Disruption of Notch signaling results in improper segmental segmentation and the bony malformations and fusions of the spine and ribs as seen in Spondylocostal Dysostosis. Mutations in the identified genes account for approximately 25% of Spondylocostal Dysostosis cases. The researchers suggest that other genes involved in Notch signaling may contribute to this condition.

Spondylocostal Dysostosis Diagnosis 

The clinic and the radiological scans serve as the foundation for the SCDO diagnosis. The radiological findings are varied and include the involvement of several spinal segments, particularly in the thoracic region, which exhibit butterfly-shaped vertebrae, fused hemivertebrae, or vertebrae, as well as various abnormalities in rib morphology. These can result in asymmetries with improper rib alignment and frequently a decrease in the overall number of ribs. They include rib growth, fusion, bifurcation, or even agenesis. Genetic testing to find mutant alleles in one of the seven currently known genes responsible for the various forms of SCDO and will confirm the diagnosis of the specific disease type.

Inheritance

Different inheritance patterns might exist for Spondylocostal Dysostosis. The majority of types, including type 1, are autosomal recessive, meaning both copies of the gene in each cell have mutations. An autosomal recessive disorder emanates from a defective gene carried from each parent, who, in most cases, are asymptomatic. Other forms of this condition have an autosomal dominant pattern of inheritance. One mutated gene copy in each cell can induce the condition in an autosomal dominant inheritance pattern. With autosomal recessive heredity, the symptoms and indications of Spondylocostal Dysostosis are often more severe.

This collection of illnesses occur due to an error in early segmentation. There are autosomal recessive and dominant types, with the latter often being more severe. The key characteristics are Hemi and Fused Vertebrae, which in extreme cases results in a short trunk. Ribs that are missing or fused appear related to spine abnormalities. Respiratory issues do not appear severe, despite the severity of the disorders, particularly in recessive instances. In contrast, the Jarcho-Levin syndrome has additional anomalies in addition to a highly severe type of Spondylocostal Dysplasia. But some instances described as having Jarcho-Levin syndrome really have a kind of Spondylocostal Dysostosis.

Immediate Care

Doctors will order the following tests on an infant with autosomal recessive Spondylocostal Dysostosis (AR SCDO) to determine the depth of their illness and their needs:

1. Evaluation of respiratory capacity, particularly if tachypnea and/or eating issues raise the likelihood of respiratory insufficiency.
2. Examination of a males to determine whether an inguinal hernia exists.
3. Parental counseling with a clinical geneticist or genetic counselor.

Spondylocostal Dysostosis Treatment

Treatments do not normally involve surgery because vertebral and rib malformations do not cause progressive difficulties in the majority of patients:

1. Respiratory support, including critical care as needed, to treat acute respiratory distress and chronic respiratory failure.
2. Regular treatment of inguinal hernia.
3. Surgical intervention becomes necessary if scoliosis becomes severe. External braces can be tried, such as using expandable prosthetic titanium ribs, or growth rods or other devices can be used if needed.

Secondary Complications should be Avoided

The most important secondary complication occurs with chronic respiratory failure caused by decreased vital capacity, which can lead to pulmonary hypertension and heart failure. These clinical problems require a specialist who will then join our team.

Surveillance

Doctors believe that that continued observation of children with breathing and spinal curvature conditions should be ongoing. Parents and caregivers must watch out for the symptoms of inguinal hernia and any associated consequences.

Managing Pregnancy 

Nearly all SCDO patients have relative truncal shortening, and some have low stature in general. Although there is no published study on this topic, for afflicted women, pregnancy may result in difficulties with excessive intraabdominal pressure. Offering spinal and/or epidural anesthesia is probably fraught with difficulty given how the spine is twisted. The administration of spinal anesthetic has proven successful, nevertheless.

Genetic Counseling

Genetic counseling provides important information to families on the implications of genetic abnormalities. This education is very important for families to make educated medical and personal decisions. Addressing genetic risk assessment and the use of family history and genetic testing to explain the genetic status of family members is very important when considering extending the family. It is not intended to cover all potential personal, cultural, or ethical difficulties or to replace expert genetics advice.

For providing cutting-edge pediatric orthopedic care, Medical City Children’s Orthopedics and Spine Specialists has received recognition from its peers and the community. Families come from all over the world to consult with our skeletal dysplasia specialists. Even the most uncommon skeletal dysplasia, like Spondylocostal Dysostosis, may be diagnosed through our genetics laboratory. After determining a child’s health, our care teams collaborate to develop a specialized treatment strategy — tailored to the family’s requirements. Our recognized pediatric orthopedic specialists will lead and direct the treatment.  Spondylocostal Dysostosis may vary and evolve over time; thus, Medical City Children’s Orthopedics and Spine Specialists has developed one of the best pediatric imaging systems in the world to monitor and record changes in children’s bodies.

We have offices in Arlington, Dallas, Flower Mound, Frisco, and McKinney, TX.  We urge you to give us a call and make an appointment if your child has a genetic condition.

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Footnote:

National Institute of Health: Spondylocostal Dysostosis