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Genetic and Rare Diseases Information Center (GARD)

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Hereditary multiple osteochondromas


Other Names for this Disease
  • Hereditary multiple exostoses
  • Hereditary multiple exostosis
  • HMO
  • Multiple exostoses
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Overview


Hereditary multiple osteochondromas (HMO) (formerly called hereditary multiple exostoses) is a genetic condition in which people develop multiple benign (noncancerous) bone tumors that are covered by cartilage (called osteochondromas). The number and location of osteochondromas varies greatly among affected individuals. These tumors are not present at birth, but almost all affected people develop multiple osteochondromas by the time they are 12 years old. Once the bones stop growing, the development of new osteochondromas also usually stops. Osteochondromas can cause abnormal growth of the arms, hands, and legs, which can lead to uneven limb lengths (limb length discrepancy) and short stature. These tumors may cause pain, limit joint movement, and exert pressure on nerves, blood vessels, and surrounding tissues. Osteochondromas are typically benign; however, researchers estimate that people with HMO have about a 1% lifetime risk of these tumors becoming a cancerous osteochondrosarcoma. HMO is caused by mutations in the EXT1 and EXT2 genes and is inherited in an autosomal dominant pattern.[1]
Last updated: 6/1/2011

References

  1. Schmale GA, Wuyts W, Chansky HA, & Raskind WH. Hereditary multiple osteochondromas. GeneReviews. September 2008; http://www.ncbi.nlm.nih.gov/books/NBK1235. Accessed 6/27/2011.
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Basic Information

  • Genetics Home Reference (GHR) contains information on Hereditary multiple osteochondromas. This website is maintained by the National Library of Medicine.
  • The National Organization for Rare Disorders (NORD) is a federation of more than 130 nonprofit voluntary health organizations serving people with rare disorders. Click on the link to view information on this topic.

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