|MULTIPLE HEREDITARY EXOSTOSES
Jake – Seventh Grade
|MHE or Multiple Hereditary Exostoses is a disorder of bone growth that is inherited from one parent. Multiple means many, hereditary means inherited and exostoses are bone tumors or osteochondroma. The bone tumors can vary in size and grow out or at an angle from the normal bone. Any bone can be affected; however, the long bones are the most commonly affected. Those noticed most are growths on the legs, arms, fingers, toes, ribs, pelvis and shoulder blades. Tumors grow near the growth plates of the bones, so the joints appear to be affected. The tumors can cause stunted growth, deformity of bones and restriction of joints and nerves. Patients can be diagnosed with MHE from birth and most of the population is diagnosed by twelve years of age.
MHE is a rare disorder; it is listed in the National Organization for Rare Disorders. One general hospital in the U.S.A, reported 1 in 90,000 patients are treated for MHE. About one out of 100,000 people in Europe have MHE; in Washington one out of 50,000 have MHE. It occurs equally between males and females, but is more severe in males. It only takes one parent with MHE to have an offspring with MHE. It is a dominant trait that has a 50% chance of showing in the offspring of a parent with MHE. Ten percent of people with MHE do not have a family history of the disorder. This is called spontaneous mutation, a genetic problem arose in that person and was not from a parent.
MHE is very painful sometimes, when you are in a physical activity. This happens because they grow near joints and muscles, which are inflamed with the movement. The tumors make the growth or part of the growth weaken. Because of this MOST people with MHE are shorter than MOST people without MHE. When your legs are uneven it can be caused by tumors on the fibula and the tibia. This may cause your legs to bow. People with MHE could have strange looking or bumpy, lumpy body parts. If a tumor is close to a joint it will limit your movement. Some children will have few symptoms of MHE while others are severely affected. Some of them have problems walking, writing, grasping, running, lifting, carrying, bending, kneeling, and other motor movements.
Research is being done in California and in Texas. They are growing tumors removed from MHE patients (me) to inject in lab animals. From this research they have found that three chromosomes cause MHE. The genes that make up MHE are called EXT1 and EXT2 found on chromosomes 8 and 11. About 70 mutations are now found in these genes. 49 different mutations have been described in EXT1 and 25 on EXT2. Some of the research is based on the cells, called chondrocytes, that control your bone growth to identify the normal function of EXT1 and EXT2 genes. The chondrocytes in a person with MHE function differently than a normal person’s chondrocytes. With research we hope to find a cure to stop the chondrocytes from acting differently.
Chansky, Howard “Hereditary Multiple Exostoses”
3 August, 2000:1-11