Osteopetrosis
From Wikipedia, the free encyclopedia
| Osteopetrosis (Malignant) | |
| Classification and external resources | |
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|---|---|
| X-ray of the pelvis of a patient with osteopetrosis, adult onset form (Albers-Schonberg disease). Note the dense bones. | |
| ICD-10 | Q78.2 |
| ICD-9 | 756.52 |
| OMIM | 166600 259700 |
| DiseasesDB | 9377 |
| eMedicine | med/1692 |
| MeSH | D010022 |
Osteopetrosis, literally "stone bone", also known as marble bone disease and Albers-Schonberg disease is an extremely rare inherited disorder whereby the bones harden, becoming denser, in contrast to the more prevalent osteomalacia, in which the bones soften.
It can cause osteosclerosis.[1]
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[edit] Pathogenesis
Normal bone growth is achieved by a balance between bone formation by osteoblasts and bone resorption (break down of bone matrix) by osteoclasts. In osteopetrosis, the number of osteoclasts may be reduced, normal, or increased. Most importantly, osteoclast dysfunction mediates the pathogenesis of this disease.
The exact mechanism is unknown. However, deficiency of carbonic anhydrase in osteoclasts is noted. The absence of this enzyme causes defective hydrogen ion pumping by osteoclasts and this in turn causes defective bone resorption by osteoclasts (acidic environment is needed for dissociation of calcium hydroxyapatite from bone matrix and its release into blood circulation). Hence, bone resorption fails while its formation persists. Excessive bone is formed.[2]
[edit] Symptoms
Despite this excess bone formation, people with osteopetrosis tend to have bones that are more brittle than normal. Mild osteopetrosis may cause no symptoms, and present no problems. However, serious forms can result in stunted growth, deformity, increased likelihood of fractures, and anemia. It can also result in blindness, facial paralysis, and deafness, due to the increased pressure put on the nerves by the extra bone.
[edit] Variations
There are several forms:
| Name | OMIM | Gene |
|---|---|---|
| OPTA1 | 607634 | LRP5 |
| OPTA2 | 166600 | CLCN7 |
| OPTB1 | 259700 | TCIRG1 |
| OPTB2 | 259710 | TNFSF11 |
| OPTB3 | 259730 | CA2 (renal tubular acidosis) |
| OPTB4 | 611490 | CLCN7 |
| OPTB5 | 259720 | OSTM1 |
| OPTB6 | 611497 | PLEKHM1 |
| OPTB7 | 612301 | TNFRSF11A |
[edit] Differential diagnosis
The differential diagnosis includes other disorders which can cause diffuse osteosclerosis, such as hypervitaminosis D, and hypoparathyroidism, Paget's disease, diffuse bone metastasis of breast or prostate cancer (which tend to be osteoblastic while most metastases are osteolytic), intoxication with fluoride, lead or beryllium, and hematological disorders such as myelofibrosis, sickle cell disease and leukemia.
[edit] Treatment
There is no cure.
If complications occur or in children, patients can be treated with vitamin D. Gamma interferon has also been shown to be effective, and it can be associated to vitamin D. Erythropoetin has been used to treat any associated anemia. Corticosteroids may alleviate both the anemia and stimulate bone resorption. Fractures and osteomyelitis can be treated as usual.
[edit] Notable cases
[edit] See also
[edit] References
- ^ Lam DK, Sándor GK, Holmes HI, Carmichael RP, Clokie CM (2007). "Marble bone disease: a review of osteopetrosis and its oral health implications for dentists". J Can Dent Assoc 73 (9): 839–43. PMID 18028760. http://www.cda-adc.ca/jcda/vol-73/issue-9/839.html.
- ^ Robbins Basic Pathology by Kumar, Abbas, Fausto, and Mitchell, 8th edition
- ^ "Marin County artist Laurel Burch dead at 61 of rare bone disease". http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/09/23/BAH2S9B1N.DTL. Retrieved on 2007-12-23.
[edit] External links
- International Osteopetrosis Association
- http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Osteopetrosis
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