Cleidocranial dysostosis, also called Cleidocranial dysplasia, is a hereditary congenital disorder

Congenital disorder

A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...

 due to haploinsufficiency

Haploinsufficiency

Haploinsufficiency occurs when a diploid organism only has a single functional copy of a gene and the single functional copy of the gene does not produce enough of a gene product to bring about a wild-type condition, leading to an abnormal or diseased state...

 caused by mutations in the CBFA1 gene also called Runx2,http://www.cafamily.org.uk/Direct/c37.html located on the short arm of chromosome 6.

It is usually autosomal dominant, but in some cases the cause is not known.

Presentation

Cleidocranial dysostosis is a general skeletal condition so named from the collarbone (cleido-) and cranium deformities which people with it often have. Common features are:

• Partly or completely missing collarbones. If the collarbones are completely missing or reduced to small vestiges, this allows hypermobility
  Hypermobility
  Hypermobility describes joints that stretch farther than is normal. For example, some hypermobile people can bend their thumbs backwards to their wrists, bend their knee joints backwards, put their leg behind the head or other contortionist performances...
  
   of the shoulders including ability to touch the shoulders together in front of the chest.
• A soft spot or larger soft area in the top of the head where the fontanelle
  Fontanelle
  A fontanelle is an anatomical feature on an infant's skull.-Anatomy:Fontanelles are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The ossification of the bones of the skull causes the...
  
   failed to close, or the fontanelle closes late.
• Bones and joints are underdeveloped. People are shorter and their frames are smaller than their siblings who do not have the condition.
• The permanent teeth
  Permanent teeth
  Permanent teeth are the second set of teeth formed in humans. There are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors.The first...
  
   include supernumerary teeth
  Hyperdontia
  Hyperdontia is the condition of having supernumerary teeth, or teeth which appear in addition to the regular number of teeth.-Types:Supernumerary teeth can be classified by shape and by position...
  
  . Unless these supernumeraries are reabsorbed before adolescence, they will crowd the adult teeth in what already may be an underdeveloped jaw. In that case, the supernumeraries will probably need to be removed to provide space for the adult teeth.
• Permanent teeth
  Permanent teeth
  Permanent teeth are the second set of teeth formed in humans. There are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors.The first...
  
   not erupting
• Bossing (bulging) of the forehead
  Forehead
  For the Arsenal striker see GervinhoIn human anatomy, the forehead is the fore part of the head. It is, formally, an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp...
  
  .
• Hypertelorism
  Hypertelorism
  Hypertelorism is an abnormally increased distance between two organs or bodily parts, usually referring to an increased distance between the orbits . In this condition the distance between the inner eye corners as well as the distance between the pupils is greater than normal...
  
  

Notable cases

The comedian

Comedian

A comedian or comic is a person who seeks to entertain an audience, primarily by making them laugh. This might be through jokes or amusing situations, or acting a fool, as in slapstick, or employing prop comedy...

 Emmett Furrow has no collarbones and uses the resulting extra shoulder mobility in comedy routines. http://www.roadcomics.com/greenroom/board/showthread.php?s=752a603abccbe75cc670c564ca8dc6b6&threadid=4888&perpage=15&pagenumber=1 (2nd message); see also
YouTube video

At the rescue of Jessica McClure

Jessica McClure

Jessica McClure Morales became famous at the age of 18 months after falling into a well in the backyard of 3309 Tanner Dr. Midland, Texas, on October 14, 1987. Between that day and October 16, rescuers worked for 58 hours to free "Baby Jessica" from the eight-inch-wide well casing below the ground...

, Ron Short, a muscular man (a roofing contractor) who was born without collarbones because of cleidocranial dysostosis and so could collapse his shoulders to work in cramped corners, arrived at the site and offered to go down the shaft; they accepted his offer, but did not use it.

External links

• http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Cleidocranial+Dysplasia
• http://www.cafamily.org.uk/Direct/c37.html
• The National Craniofacial Association
• http://www.medterms.com/script/main/art.asp?articlekey=6549
• http://www.dental.mu.edu/oralpath/lesions/cleidocraniadys/cleidocraniadys.htm
• http://www.ncbi.nlm.nih.gov/books/bv.fcgi?indexed=google&rid=gene.chapter.ccd
• Medical Imaging on CCD
• GeneReviews/NCBI/NIH/UW entry on Cleidocranial Dysplasia
• Radiology of CCD Images from MedPix