condition. The permanent teeth include supernumerary teeth. Unless these supernumeraries are removed they will crowd the adult teeth in what already may be an underdeveloped jaw. If so, the supernumeraries will probably need to be removed to make space for the adult teeth. Up to 13 supernumerary teeth have been observed. Teeth may also be displaced. Cementum formation may be deficient. Failure of eruption of permanent teeth. Bossing (bulging) of the forehead. Open skull sutures, large fontanelles. Hypertelorism. Delayed ossification of bones forming symphysis pubis, producing a widened symphysis. Coxa vara can occur, limiting abduction and causing Trendelenburg gait. Short middle fifth phalanges, sometimes causing short and wide fingers. Vertebral abnormalities. On rare occasions, brachial plexus irritation can occur. Scoliosis, spina bifida and syringomyelia have also been described. Wide nasal bridge Crooked teeth Increased risk of flat foot and knee deformities High risk of hearing loss caused by infections Decreased bone density, resulting in increased risk of fractures Other features are: parietal bossing, basilar invagination (atlantoaxial impaction), persistent metopic suture, abnormal ear structures with hearing loss, supernumerary ribs, hemivertebrae with spondylosis, small and high scapulae, hypoplasia of illiac bones, absence of the pubic bone, short / absent fibular bones, short / absent radial bones, hypoplastic terminal phalanges. Genetics CCD is usually autosomal dominant, but in some cases its cause is not known. The main mechanism is thought to involve haploinsufficiency caused by mutations in CBFA1 (also known as Runx2), a gene located on the short arm of chromosome 6 (6p21), which encodes a transcription factor required for the differentiation of stem cells into osteoblasts. This results in delayed ossification of midline structures of the body and ensuing defects in membranous and endochondral bone formation. Diagnosis Different features of the dysostosis are significant. Radiological imaging helps confirm the diagnosis. During gestation (pregnancy), clavicular size can be calculated using available nomograms. Wormian bones can sometimes be observed in the skull. Diagnosis of CCD spectrum disorder is established in an individual with typical clinical and radiographic findings and/or by the identification of a heterozygous pathogenic variant in RUNX2 (CBFA1). Treatment Around 5 years of age, surgical correction may be necessary to prevent any worsening of the deformity. If the mother has dysplasia, caesarian delivery may be necessary. Craniofacial surgery may be necessary to correct skull defects. Coxa vara is treated by corrective femoral osteotomies. If there is brachial plexus irritation with pain and