What is DMD?
From here you can find information on Duchenne and Beckers Muscular Dystrophy.
We have included an overview of DMD & Beckers MD, a DMD Fact Sheet, a Beckers MD Fact Sheet and you can also download a word file courtesy of the Parent Project which covers the basic science of DMD.
DMD: Duchenne Muscular Dystrophy
Duchenne Muscular Dystrophy is the most common form of Muscular Dystrophy. It usually only affects boys although rare...it is known to affect girls also. It is an inherited disease. Boys with DMD develop weak muscles because the muscle fibres that were present at birth are destroyed.
Boys with DMD do not have the genetic material that gives the message to the body to make a protein called dystrophin. Without dystrophin, Duchenne muscular dystrophy occurs.
During the first few years of life, muscle fibres that break down are continually replaced. Unfortunately, the body has a limited capacity to replace these muscle fibers. Eventually the rate of regeneration cannot keep up with the rate of degeneration. As a result, muscles become weaker.
Although DMD is present from birth, the child appears perfectly normal. Problems usually do not show up until eighteen months to four years of age. Most boys do not walk until eighteen months or later.
During the first few years of life these children have difficulty climbing, getting up from the floor and are unable to keep up with their friends and can often be thought clumsy and lazy. Some boys also have enlarged calf muscles which is due mainly to an increase in fatty tissue in the muscle. This is a sign of disease rather than of good strength.
Some boys also have problems with delay in mental or language development.
Diagnosing DMD
A diagnosis of DMD is made and confirmed with two tests:
A Creatine kinase (CK) test, which is a blood test that looks at the level of CK. Normally there is only a small amount in the blood but in boys with DMD, there may be 10 to 100 times the normal amount.
A Muscle Biopsy, where a small piece of muscle is removed then cut in thin strips and stained with a series of special dyes to show the different types of muscle fibres.
We have provided a page which depicts Dystrophic Muscle taken from a muscle biopsy.
Disease Progression
Between the ages of 3 and 6 many boys seem to be improving but by the age of 6 or 7 deterioration becomes obvious. The child finds it harder to walk long distances and there is increasing difficulty walking up stairs, rising from the floor and playing sport. The child's walk becomes more of a waddle, toe-walking is noted and the child has an inward curving of the lower back.
A wheelchair will usually be needed between the ages of 9 and 13. As chest muscles become weaker it becomes more difficult to move air in and carbon dioxide out of the lungs and there is increasing difficulty fighting off infections. Death is usually due to these problems. The age of death varies from the late teens to the mid twenties. Although there are young men with DMD who live beyond this time.
An Inherited Disease
Duchenne Muscular Dystrophy is described as an X-linked recessive inherited disease.
This means that the disease is passed on from the mother through her X chromosome. She is known as a carrier. If the mother passes this X chromosome to a daughter she would not be affected as she has a second X chromosome to control the production of dystrophin. Although her daughter would herself then be a carrier.
In one third of all boys with this disease it has been caused by a new mutation so there would be no history in the family of this disease.
Currently there is no cure for this disease but there are many research projects being undertaken all over the world so we can remain cautiously optimistic for the future.
Additional Information
You may wish to print out our DMD Fact Sheet for a quick reference or to pass on to someone else.
We also have a WORD file you can download courtesy of the Parent Project - Muscle Structure/Function & DMD
Some of the information on this page was taken from the book - Duchenne Muscular Dystrophy: A Guide for Parents. Published by The MDA of Victoria.
