Osteopetrosis (plural osteopetroses) is a rare inherited disorder that makes bones increase in both size (mass) and fragility.
Osteopetrosis is also called chalk bones, ivory bones, or marble bones.
Osteopetrosis occurs when there is a failure in bone resorption.
Other forms of osteopetrosis progress at a more rapid pace and destroy bone structure, which can involve bones throughout the body, although the lower jaw is never affected.
Severe malignant infantile osteopetrosis (early-onset osteopetrosis) is the most severe form of osteopetrosis.
Early-onset osteopetrosis can be a fatal condition, with death occurring before the age of two.
Although this form of osteopetrosis is called "malignant," it is not a type of cancer.
Intermediate osteopetrosis generally appears in children under age ten.
This condition is usually less severe than early-onset or malignant infantile osteopetrosis and is not normally life-threatening.
Adult (delayed-onset) osteopetrosis may not become evident until after age 20.
Many people with adult osteopetrosis are diagnosed only when abnormalities are discovered on x rays taken for other purposes.
There are two distinct types of adult osteopetrosis (types I and II).
The incidence of osteopetroses is not known, although it is estimated that adult osteopetrosis occurs in about one of every 1,250 individuals.
Worldwide malignant infantile osteopetrosis occurs in about one in 100,000 to 500,000 births, making it exceedingly rare.
Osteopetrosis is the result of a genetic defect that causes the body to add new bone more rapidly than existing bone disintegrates.
Osteopetrosis is usually diagnosed when x rays reveal abnormalities or increases in bone density.
Interferon gamma-1b (Actimmune) is the only drug approved by the United States Food and Drug Administration (FDA) to treat osteopetrosis.
Injections delay the progress of severe osteopetrosis in both children and adults.
Bone marrow transplantation (BMT) is the only therapy that can completely cure severe malignant infantile osteopetrosis.
The survival rate for children with osteopetrosis who undergo BMT is 40 to 70 percent.
The severity of anemia seems to determine the course of an individual's osteopetrosis.
About two-thirds of children who have severe malignant infantile osteopetrosis die before age ten unless they have a successful bone marrow transplant.
Osteopetrosis is an inherited disease that cannot be prevented.
"Osteopetrosis." eMedicine.com, March 19, 2002.
"Information for Patients about Osteopetrosis."
Osteopetrosis: The congenital form of osteopetrosis is rare and involves the formation of overly dense but fragile bones that can lead to frequent fractures, blindness, deafness, and strokes.
The more severe form of congenital osteopetrosis is usually fatal within the first ten years of life unless successfully treated with a bone marrow transplant.
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