These disorders occur when the body does not recycle old bone cells.
Typical symptoms include impaired bone growth and thick bones that easily break.
The diagnosis is based on symptoms and x-rays.
Osteopetrosis that occurs in infancy may be fatal if not treated.
There is no cure, but some treatments can help relieve problems caused by the disorders.
(See also Overview of Bone Disorders in Children Overview of Bone Disorders in Children Bone disorders can be caused by injury, infection, or cancer, be inherited, occur as part of a child’s growth, or occur for no known reason. Some bone disorders can cause pain and difficulty... read more .)
Osteopetroses result from abnormalities in certain genes. These abnormal genes are hereditary. That is, they may be passed down from parent to child.
Bone cells constantly but slowly form, live for a period, and then are reabsorbed, a recycling process. In osteopetrosis, the body does not recycle old bone cells. The result is increased density or thickness of the bones and an alteration in how the bones are shaped. These changes make bones weaker than normal. The dense bone tissue also crowds out the bone marrow, which is where blood cells are formed.
Osteopetroses range from mild to severe and can even be life threatening. Symptoms of osteopetroses may begin in infancy (early onset) or later in life (delayed onset).
Symptoms of Osteopetroses
Although osteopetroses comprise a range of different disorders, many of the same symptoms develop in most of them. Bone growth is usually impaired. Bones thicken and break easily. Formation of blood cells may be impaired because there is less bone marrow, leading to anemia Overview of Anemia Anemia is a condition in which the number of red blood cells is low. Red blood cells contain hemoglobin, a protein that enables them to carry oxygen from the lungs and deliver it to all parts... read more , infection, or bleeding.
An overgrowth of bone in the skull can cause pressure in the skull to increase; compress nerves, causing facial paralysis or loss of vision or hearing; and can distort the face and teeth. The bones in the fingers and feet, the long bones of the arms and legs, the spine, and the pelvis may be affected.
Diagnosis of Osteopetroses
Doctors usually base the diagnosis of osteopetroses on symptoms and x-rays Plain X-Rays X-rays are high-energy radiation waves that can penetrate most substances (to varying degrees). In very low doses, x-rays are used to produce images that help doctors diagnose disease. In high... read more that show very dense or malformed bones.
When the person has no symptoms, osteopetrosis is sometimes detected only by chance, after a doctor sees very dense bones on x-rays taken for an unrelated purpose.
Prognosis for Osteopetroses
Early-onset osteopetrosis that is not treated with stem cell transplantation Stem Cell Transplantation Stem cell transplantation is the removal of stem cells (undifferentiated cells) from a healthy person and their injection into someone who has a serious blood disorder. (See also Overview of... read more usually causes death during infancy or early childhood. Death usually results from anemia, infection, or bleeding.
Late-onset osteopetrosis is often very mild.
Treatment of Osteopetroses
Sometimes stem cell transplantation
There is no definitive cure for osteopetrosis.
Corticosteroids, such as prednisone, decrease the formation of new bone cells and may increase the rate of removal of old bone cells, strengthening bones. Corticosteroids may also help relieve bone pain and improve muscle strength.
Stem cell transplantation Stem Cell Transplantation Stem cell transplantation is the removal of stem cells (undifferentiated cells) from a healthy person and their injection into someone who has a serious blood disorder. (See also Overview of... read more seems to have cured some infants with early-onset disease. However, the long-term prognosis after transplantation is unknown.
Fractures, anemia, bleeding, and infection require treatment.
If nerves going through the skull are compressed, surgery may be required to take pressure off the nerves. Surgery may also be needed to relieve increased pressure in the skull. Plastic surgery may be done to correct severe deformities of the face and jaw.
Orthodontic treatment may be needed to correct distorted teeth.