Hereditary Multiple Exostoses Details

Expanded Description

Hereditary Multiple Exostoses is a genetic bone disorder in which benign cartilage-capped bone tumors grow outward from the metaphyses of long bones, growth plates or from the surface of flat bones throughout the body.

The severity of this disease varies widely. Some patients may have as few as two tumors, but most patients develop many more and the numbers of tumors can run into the hundreds.

These cartilage-capped bone tumors are called Exostoses / Osteochondroma and may be sessile or pedunculated and vary widely in size and shape. Pedunculated Exostoses / Osteochondroma is when a stalk is present, the structure is called pedunculated. These have a Broccoli like appearance with stalk and growth towards the end of the stalk. Sessile Exostoses / Osteochondroma have a broad-base attachment to the outer bone, called the “cortex”. These have a lumpy / bumpy appearance (When no stalk is present, these are called sessile)

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 malignant tumor transformation (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 / Osteochondromas 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 chronic pain, fatigue and mobility problems throughout their lives. MHE / MO / HME is a genetic 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. 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.

Prevalence

2.0 ( Per 100,000 Population ) [Source]

Causes

There are two known genes found to cause MHE / MO / HME they are EXT1 located on chromosome 8q23-q24 and EXT2 located on chromosome 11p11-p12. Approximately 60 to 70 % of mutations are located in the EXT1 gene and 20 to 30% are located in the EXT2 gene. In 10 to 20% of the patients, no mutation is found. MHE / MO / HME is an autosomal dominant hereditary disorder. MHE / MO / HME is a genetic autosomal dominant hereditary disorder, this means that a patient with this condition has a 50% chance of transmitting the disorder onto his/her children. This is equal for both male and female patients. Normally this disorder does not skip a generation.

Mutations in the EXT1 and EXT2 genes cause Multiple Hereditary Exsotses/Multiple Osteochondroma. The EXT1 gene and the EXT2 gene provide instructions for producing the proteins exostosin-1 and exostosin-2, respectively. The two exostosin proteins bind together and form a complex found in a cell structure called the Golgi apparatus, which modifies newly produced enzymes and other proteins. In the Golgi apparatus, the exostosin 1 and 2 complex modifies a protein called heparan sulfate so it can be used by the cell.

When there is a mutation in exostosin-1 or exostosin-2, heparan sulfate cannot be processed correctly and is nonfunctional.

Disorder Symptoms

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 (Life time risk of 2%-5% reported).

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.

We don't have any symptoms yet.

Diagnosis

The diagnosis of MHE / MO / HME is most often made by a Pediatric Orthopaedic Surgeon.

Exostoses / Osteochondroma can be diagnosed via X-Ray.

The severity of this disease varies widely. Some patients may have as few asvtwo tumors, but most patients develop many more and the numbers of tumors can run into the hundreds.

Diagnostic Tests

Radiographs (X-Ray) MRI, CT, and or Genetic testing can be preformed to find the mutation located in the EXT1 or Ext2 genes.

We don't have any tests yet.

Disorder Treatments

There is no known drug treatment for MHE / MO / HME. 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.

We don't have any treatments yet.

Prognosis

No prognosis information has been added yet

Tips for Living with the Disorder

We don't have any tips yet.