Dysostosis is a medical condition affecting bone development, repair, or growth. The disorder particularly involves the impairment of proper bone ossification which is the maturation of new bone material out of primitive tissue in the form of cartilage or out of one of the primary germ layers of the body – the mesenchyme. The illness is also known as dysosteogenesis, earning its name for the defective ability to complete bone formation.

Various conditions are classified as a type of dysostosis; these include cleidocranial dysostosis, Klippel-Feil syndrome, and the Rubinstein-Taybi syndrome. The ailment is generally considered to be one that is congenital in nature, indicating that the defect is inborn and is most often caused by genetic abnormalities that predispose a fetus to the condition.

Cleidocranial dysostosis for example is a type of dysostosis characterized by deformities that affect the collarbone as well as the cranium or the skull. Patients with the disorder may present with an undersized or even completely absent collarbones, underdeveloped bones in the rest of the body, as well as fontanelles that were unable to close even beyond infancy. Klippel-Feil syndrome, another notable form of dysostosis, is characterized by conjoined cervical vertebrae. Patients with the condition have abnormally short necks as well as limited ability to move the upper portion of the back. Rubinstein-Taybi Syndrome on the other hand not only affects skeletal development but mental capacity as well. Patients present with limited ability for learning as well as short stature, small craniums, and observably enlarged thumbs.