Cleidocranial Dysostosis (Cleidocranial Dysplasia)

Cleidocranial dysostosis (cleidocranial dysplasia) is an autosomal dominant inherited condition consisting of hypoplasia or aplasia of the clavicles, delayed ossification of the cranial fontanelles, and a large, short skull. Associated features are shortness of stature, frontal and parietal bossing, failure to pneumatize the air sinuses, a high arched palate and/or clefting, mid-face hypoplasia, and failure of tooth eruption with multiple supernumerary teeth. Many of the teeth present have inherent abnormalities such as dilaceration of roots or crown gemination. Hypoplasia of secondary cementum may occur. The condition mainly, though NOT exclusively, affects membraneous bone.

Affected individuals may be 3 to 6 inches shorter than other members of their family, and may have:

• short, tapered fingers and broad thumbs;
• short forearms;
• flat feet;
• knock knees; and
• an abnormal curvature of the spine (scoliosis).

Characteristic facial features may include:

1. a wide, short skull (brachycephaly);
2. a prominent forehead;
3. wide-set eyes (hypertelorism); a
4. flat nose; and a
5. small upper jaw.

Dental abnormalities seen in cleidocranial dysplasia may include:

• delayed loss of the primary (baby) teeth;
• delayed appearance of the secondary (adult) teeth;
• unusually shaped, peg-like teeth;
• misalignment of the teeth and jaws (malocclusion); and
• extra teeth, sometimes accompanied by cysts in the gums.

Genes related to Cledocranial Dysplasia

It is transmitted as an autosomal dominant trait. CCD is caused by mutation in the RunX2 gene on Chromosome 6p21.

The RUNX2 gene provides instructions for making a protein that is involved in bone and cartilage development and maintenance. This protein is a transcription factor, which means it attaches (binds) to specific regions of DNA and helps control the activity of particular genes. Researchers believe that the RUNX2 protein acts as a "master switch," regulating a number of other genes involved in the development of cells that build bones (osteoblasts).

Some mutations change one protein building block (amino acid) in the RUNX2 protein.

Above mutations may cause..

· Delayed closure (ossification) of the space between the bones of the skull (fontanels)

· Premature closing of the coronal suture

• · Protruding jaw (mandible) and protruding brow bone (frontal bossing)
• · Wide nasal bridge due to increased space between the eyes (hypertelorism)
• · High arched palate or possible cleft palate
• · Short stature
• · Scoliosis of the spine

Problems which child would have

· Dental abnormalities - failure to lose the baby teeth (deciduous) at the expected time; slow eruption of secondary teeth; extra teeth; delayed or absent formation of teeth

• · Ability to touch the shoulders together in front of the body
• · Wide pelvic bone
• · Loose joints
• · Hearing loss and/or frequent infections