Dictionary > Multiple Hereditary Exostoses

Multiple Hereditary Exostoses

(MHE) multiple Hereditary Exostoses also often
referred to as hereditary multiple exostoses (HME)
multiple Osteochondromas (mo) is the preferred
term used by the world health organization “WHO”.
MHE / mo / HME is a genetic bone disorder in which benign cartilage-capped
bone tumors that grow outward from the metaphyses of long bones, growth
plates of long bones or from the surface of flat bones throughout the body.
An Exostosis / Osteochondroma may be sessile or pedunculated.
Sessile exostoses / Osteochondroma have a broad-based attachment to the cortex.
The pedunculated variants have a pedicle arising from the cortex that is usually directed away from the adjacent growth plate.
The pedunculated form is more likely to irritate overlying soft tissue, such as tendons, and compress peripheral nerves or vessels.
These exostoses / Osteochondroma’s 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, reported risk of 2%-5% over life time.
It is not uncommon for MHE / mo / HME patients to undergo numerous surgical
procedures throughout their lives to remove painful or deforming exostoses /
Osteochondroma’s and or to correct limb length discrepancies and improve range
of motion.
surgery, physical therapy and pain management are currently the only options
available to MHE / mo / HME patients, but their success varies from patient to
patient and many struggle with pain, fatigue and mobility problems throughout
their lives.
MHE / mo / HME is an autosomal dominant hereditary disorder.
This means that a patient with MHE / mo / MHE has a 50% chance of transmitting this disorder to his / her children.
This is equal for both male and female patients. Normally this disorder does not skip a generation.
Most individuals with MHE / mo / HME have a parent who also has the condition,
however, approximately 10% -20% of individuals with MHE / mo / HME have the condition as a result of a spontaneous Mutation 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 EXT1 gene and 20 to 30% are located
EXT2 mutation. Genetic testing, Prenatal diagnosis and Preimplantion genetic
diagnosis “PDG” are available.
The major defect in the EXT genes that cause MHE is the lack of Heparan
For more detailed information http://www.mheresearchfoundation.org

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