Fibrous Dysplasia

Fibrous dysplasia is a disorder that is not inherited but arises from bone cells that make altered bone that is weak, prone to fracture, and associated with pain, deformity, and dysfunction. The fibrous dysplasia changes can occur in a single bone (monostotic) or in several bones (polyostostic). The severity will vary based on the number of bony sites with fibrous dysplasia and their specific skeletal locations. When associated with problems in other tissues and hormones the disorder is known as McCune-Albright syndrome.

Fibrodysplasia Ossificans Progressiva (FOP)

FOP is a condition that causes bony changes to develop in the soft tissue and muscles, typically after minor injuries or trauma. The bony changes can occur anywhere in the body and can be disabling and even life-threatening. New therapies are under-going clinical trials as potential treatments for this disorder.


Osteopetroses are disorders caused by an imbalance in bone turnover, the process that coordinates the life-long cycle of bone removal and replacement that takes about 7 years in an adult. When the bone-removing cells (osteoclasts) do not function properly, too much bone accumulates and can interfere with normal function, making bones brittle and causing problems with the bone marrow, blood vessels, and nerves. New treatments are in early clinical trials.

High Bone Mass

High Bone Mass is a disorder caused by changes in either of two genes that code for sensors (receptors) that because of the gene alterations are always sending signals to make new bone. Researchers in our Division of Bone and Mineral Diseases were among the first to first to identify and describe this high bone mass disease in two families seen in our center.

These are but a few of the more than 100 rare bone disorders that are familiar to the physicians and staff of the Adult Rare Bone Disease clinic within our Bone Health Program at Washington University School of Medicine. If you cannot find what you are looking for, feel free to contact us; or visit the National Organization for Rare Disorders website (

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