More than 100 defective conditions have been found to be associated with this condition. Cleidocranial Dysplasia besides affecting the skull bones, collarbone and teeth can also affect -

1. Jawbones
2. Vertebral column
3. Pelvic or the hipbones
4. Bones of the legs

There maybe also a wide pubic symphysis, short middle digit of the fifth fingers, delayed skeletal maturation, deafness, and broad nose with depressed bridge, retarded growth..

Some of the classic features of this condition include -

Shoulder The most striking or the diagnostic feature of Cleidocranial Dysplasia happens to be the complete absence of the clavicle or the collarbone. This is seen in almost 15 percent of the cases. In others, there is a partial absence of these bones or if present they are very thin. A person affected by this condition is able to bend his shoulder and the arm with it almost in any diectiion and their will.

Head and Neck

In the skull there are sutures or fissures in the bone of a newborn called the fontanelles. These are supposed to close soon after birth but in this condition these can remain open for a long time; resulting in large appearance of the skull or the head.

Other sutures between the skull bones also do not close leading to the formation of abnormal bones called wormian bones.

The sagittal suture, which is present at the top of the skull between the parietal bones, is often sunken deep within the skull giving it a flat appearance.

The air pockets or sinuses in the face bones such as the frontal, maxillary and the ethmoid bones can be underdeveloped.

Inside the oral or mouth cavity the upper palate may be split and gives rise to a condition called the cleft palate.

The upper jawbone or the maxilla is severely underdeveloped in relation to the lower jawbone or the mandible and the face looks unduly small.

Teeth

Primary or the milk teeth are retained for a long time can this results in delayed or no eruption of the permanent teeth. When these teeth do erupt, they have very thin roots and are prone to fracture if stressed. Dental root and crown abnormalities are also present. Radiographs of the jaw area often reveal many unerupted teeth embedded in the bone.

Sometimes extra teeth maybe present in large numbers giving rise to what are called supernumerary teeth.

Muscular Development

Cleidocranial Dysplasia basically affects the entire skeleton and could also affect the muscles. This is because the bones are underdeveloped and this results in muscular development getting affected. It is not uncommon to have reduced muscle mass in the region of the affected bones.

Differential Diagnosis

Another disease called the pycnodystosis or the Maroteaux-Lamy syndrome presents identical features as Cleidocranial Dysplasia. However Maroteaux-Lamy syndrome is differentiated by presence of dwarfism. Additionally, patients affected by this syndrome have dense and fragile bones.