(MO), also known as '''Hereditary Multiple Exostoses ''' (HME), and interchangeably as Multiple Hereditary Exostoses (MHE), is a congenital medical condition whereby multiple
Exostoses (bony spurs or lumps, also known as osteochondromas) develop on the bones of a child. Generally, when a person with MO reaches maturity, and their bones stop growing, the exostoses also stop growing.
It is estimated to occur in 1 in 50,000 people. A person with MO is more likely to develop a form of bone cancer called
Chondrosarcoma as an adult.
Multiple Osteochondromas (MO) is the preferred term used by the
World Health Organization .
MO is a genetic bone disorder in which benign cartilage-capped bone tumors grow outward from the metaphyses of long bones, growth plates of long bones or from the surface of flat bones throughout the body. If necessary, the exostoses can be removed by surgery.
These Exostoses / Osteochondromas can cause numerous problems, including: compression of peripheral nerves or blood vessels; irritation of tendons and muscles resulting in pain and loss of motion; skeletal deformity; short stature; limb length discrepancy; chronic pain and fatigue; mobility issues; early onset arthritis; and an increased risk of developing chondro- sarcoma, with a reported risk of 2%-5% over life time.
It is not uncommon for MO patients to undergo numerous surgical procedures throughout their lives to remove painful or deforming Exostoses / Osteochondromas, correct limb length discrepancies or improve range of motion.
Surgery, physical therapy and pain management are currently the only options available to MO patients, but success varies from patient to patient and many struggle with pain, fatigue and mobility problems throughout their lives.
MO is an autosomal dominant hereditary disorder. This means that a patient with MO has a 50% chance of transmitting this disorder to his or her children.
This is equal for both male and female patients. Normally this disorder does not skip a generation.
Most individuals with MO have a parent who also has the condition, however, approximately 10% -20% of individuals with MO have the condition as a result of a spontaneous mutation and are thus the first person in their family to be affected.
There are two known Genes that cause this disease EXT1 located on chromosome 8q23-q24 and EXT2 located on chromosome 11p11-p12. Approximately 60 to 70% are located in the EXT1 gene and 20 to 30% are located in the EXT2 mutation. Genetic Testing, Prenatal Diagnosis and Preimplantion Genetic Diagnosis "PDG" are all available.
The major defect in the EXT genes that cause MHE is the lack of
Heparan Sulfate .
The MHE Research Foundation includes Comprehensive information on Research, MHE Conferences, Orthopeadics, Genetics and Chronic Pain associated with this disorder.
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- http://www.MHEResearchFoundation.org - MHE Research Foundation's Website
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