Definition
Hereditary multiple exostoses (HME) refers to a group of disorders characterized by abnormal bone growth.
Inherited
MHE is a condition that is passed by the genes of the affected parent to their children. It is called an ~autosomal dominant~ disorder which means that if one parent has the condition, chances are fifty percent that any child could also develop MHE. Occasionally, a patient will develop multiple exostoses with no previous family history of MHE. This situation is described as a spontaneous mutation meaning a genetic problem arose in that person without being inherited from a parent. Recently chromosomes (the packages that carry genes) 8, 11 and 19 have all been shown to be locations where the genetic information for MHE comes from. Some researchers feel there actually may be different types of MHE each caused by different genes at these locations.
Extosis
An exostosis is a bone growth that is abnormal or different from the underlying architecture of the bone. These "abnormal growths" are not cancer, They are benign. Sometimes doctors refer to exostoses as "tumors" which like exostose is a general term meaning abnormal growth. It is important to remember that not all "tumors" are cancer. Most tumors, like the exotoses of MHE, are benign. Exostoses start near the growth centers of bones which are near the ends of the bones, which is why bumps grow near the joints. They can be rounded or sharp and continue to grow while a child is growing. When a person is full grown, exostoses also stop growing.
