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What is it? - Multiple Hereditary Exostoses is an inherited disorder of bone growth. MHE can be referred to by various names such as Heredity Multiple Exostoses, Hereditary Multiple Osteochondromata, Multiple Carthaginous Exostoses, etc. People who have MHE grow exostoses, or bony bumps, on their bones which can vary in size, location and number depending on the individual. Although any bone can be affected, the long bones (legs, arms, fingers, toes), pelvis and shoulder blades are the most common, while the face and skull are generally unaffected. Boys and girls can both be affected. Older literature claimed that boys were more severely troubled by MHE, but bigger series of patients studied recently do not support this theory.

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.

What problems are caused by MHE? - MHE can be troublesome. Because the exostoses grow near the growth centers of the bone, they can make the growth center grow poorly, or only part of it grow poorly. This makes a lot of people with MHE somewhat shorter than average or have bowed arms or legs. Often, the forearm will bow out toward the lime finger, or the legs can become knock kneed. This is frequently concerning, but function is often normal though cosmetically, the bowing can be very troubling. Sometimes folks with MHE get stiff, especially in the elbows and hips, usually because their exostoses block some of their motion. While children are growing, exostoses can be painful. They seem to be very sensitive to getting bumped. Kids often develop exostoses on the inside of their knees and these can hit together when they run, which hurts!

Sometimes exostoses grow near nerves or tendons and press on them. In these cases, they often need to be removed so they won't damage the structure laying over them.

The most frightening complication of MHE is also one of the most uncommon. Rarely (less than 1% of the time), the benign exostoses of MHE can become a malignant tumor called chondrosarcoma. This happens almost always after adulthood when skeletal growth has ceased. Usually, patients who develop chondrosarcoma are in their 20's to 50's. If a person with MHE notices that an exostoses is getting bigger or painful after they have stopped growing they should get to their doctor! Growth and pain are two important warning signs that a benign tumor has become malignant. Chondrosarcoma is very rare, but it is something MHE families must know about.

Treatment - Some people with MHE never require any treatment. They learn to compensate for deformity or decreased range of motion so they function normally. When deformity does occur, it often happens so slowly that the patient can compensate for it well, while others may require surgery to help them.

If an exostoses is painful, pressing on an important structure, cosmetically unattractive or if easily bumped, it can be surgically removed. Once removed, exostoses can reoccur (about 20 - 50% of the time), but may not regrow to a size large enough to be symptomatic. Removal itself is usually a fairly small procedure; some are removed without ever staying overnight in the hospital.

If an exostoses causes a growth abnormality, like bowing, sometimes just removing the exostoses early enough will allow the bone to straighten itself out and remodel as the child grows. Some bowing is so severe that not only must the exostoses be removed, but also the bone must be straightened. This can be done by either cutting the bone, straightening it and then holding it in place while it heals or if the child is still growing by changing the rate of growth on one side of the growth plate. Currently there are several options and your doctor should be able to explain them to you.

If an exostoses does become malignant and turn into a chondrosarcoma then it must be removed. A specialist in orthopedics and bone tumors would be required to help with this.

Outlook - Scientists throughout tho world have demonstrated the genes for MHE are found on three different chromosomes. This leads to the belief that MHE is caused by at least three different genes with one or more on each chromosomes. It is known that the genes are located on chromosome numbers 8, 11 and 19 with number 8 being the most common location found.

Continuing research of the genes and how the proteins encode for them will give tremendous insight into the growth of cells. This information is important since MHE is a problem with the growth of cells.

Understanding the gene and the function of its protein might eventually provide the knowledge leading to actual treatment. The gene mapping studies will serve as the basis for the testing of children at risk for MHE. At the time of this publication, the availability of such testing is limited to a research setting. However, your physician could be equipped to perform this test in the near future. Information from this test could lead to the prevention of the development of exostoses and their complications.

A national support group for MHE was established in 1993. This support group is for any family involved with MHE, but not necessarily afflicted. For more information please write or call.

MHE Family Support Group

Chele Zelina
8838 Holly Lane
Olmsted Falls, Ohio 44138

440 - 235 - 6325

The Support group is registered with the The Genetic Alliance.

Our thanks to Dr. Kristen Carroll of Shriner's Hospital in Salt Lake City, Utah for making this brochure possible.

Links to other sites with information on MHE.

MHE Onelist E-Mail Support Group
This international support group offers the ability to communicate with others via e-mail. The group is very interactive, and topics range from sharing information on the effects of MHE and how different people cope with them, to offering support during times of crisis. The group offers a weekly "chat" for members. The MHE Onelist, founded by Bill Daniels in July of 1999, has grown to 80 families in seven months, and continues to grow. The YahooGroups E-Mail Support Group hosts a weekly online Chat every Saturday night at 8:00 p.m., CST . To join in the chat, go to: To join the MHE YahooGroups E-Mail Support Group, go to: Type: M_H_E in search field. For more information, please contact:

Chele Zelina
8838 Holly Lane
Olmsted Falls, Ohio 44138
Telephone: 440-235-6325 -- e-mail:
ICQ Pin: 30070265

MHE and Me
A Support Group for Kids with Multiple Hereditary Exostoses and their Families This group, founded in July of 1999 by two "MHE Moms", is dedicated to providing peers for children dealing with this disorder, and to creating a supportive community of people who understand what it means to live with MHE. The MHE and Me web site fetures The Bumpy Bone Club, where children can share their stories, poems, thoughts, and where adults with MHE can share their Bumpy Bone stories and experiences with the kids. The site also features The MHE and Me Handbook: A Guide for Families, Frinds, Teachers and Classmates. This printable guide is proving to be a useful tool for many MHE families. For families without Internet access, copies of the Handbook and other features of the site are available by request. MHE and Me Web Site: For more information, please contact:

Susan Wynn
14 Stony Brook Drive
Pine Island, NY 10969
914-258-6058 -- e-mail:

Cassie Esselink
109 Washington
Mt. Clemens, MI 48043
810-954-1059 -- e-mail:

MHE Webring and Yahoo! Club
These sites were created by Dawn, a young woman with MHE. The Yahoo! Club is an on-line meeting place for those affected by MHE, where they can leave messages on the message board and sometimes Chat with other members. The Webring contains links to several MHE-related sites.

MHE Webring:
Yahoo! Club:

HME Support Group
This United Kingdom-based support group has a very informative web site. In addition to information about Hereditary Multiple Exostoses, they also maintain a Notice Board to assist those in the international community in finding others who may be closer to home.
Hereditary Multiple Exostoses Support Group (United Kingdom)

Elizabeth Munroz's Page on MHE
A page covering five generations of a family with MHE. Also the writers own experiences.
Elizabeth Munroz's page on MHE

Medical Links contains a medical oriented page with descriptions of type1 (chromsome 8) and type2 (chromosome 11) MHE. It is at the Wells Lab Human Genetics Program, University of Houston. contains an online html version of "Wheeless' Textbook of Orthopaedics". Check out the entry under Multiple Cartilaginous Exotoses. Also there are many links to other orthopaedic related sites.

MHE Coalition Newsletter

The MHE coalition is the web page for the MHE family support group. They publish a good newsletter and their page has a link to their current newsletter and to back issues. Read their page for more good information on MHE, and how to contact them.