Each form of muscular dystrophy is caused by a defect in a specific gene. Genes are the body's basic units of heredity that are found in most cells in the body. They determine physical characteristics such as our height, eye color and muscle development. Scientists have determined that this disease is caused by the failure of a specific, identifiable gene to produce a vital muscle related protein called dystrophin.
When functioning properly, the Duchenne gene carries instructions for assembling a muscle protein known as dystrophin. Mutations in this gene result in dystrophin deficiency which constitutes the pathogenic basis of DMD. Dystrophin is usually absent or severely deficient in a person with DMD while those with Becker muscular dystrophy typically have some altered expression of dystrophin. Without dystrophin the muscle fibers lose the ability to regenerate and are eventually replaced by fat and fiber tissue.
You can not catch DMD - you are born with it. DMD is not contagious - it is an inherited disease. There are no environmental elements we know of today that cause DMD.
Back To DMD Info Site Main Menu
DMD is an inherited disease. Each person has 46 chromosomes, 23 from the mother and 23 from the father. Chromosomes are found in the cell nucleus and consist of long chains of nucleic acids. 22 of these chromosome pairs appear the same in both sexes but differ at the molecular level (the sequence of chemical bases in their DNA - discussed later). These are known as autosomal chromosomes . Sex is determined by the remaining pair of chromosomes. Women have a pair of X sex chromosomes. Men have one X chromosome and a shorter chromosome called Y.
The DMD gene is found on the X chromosome. The gene is passed on by an X linked inheritance pattern. X linked diseases occur because of genetic defects located on the X chromosome. Boys have a 50% chance of being born with this affected gene and girls have a 50% chance of being a carrier. Complex analysis of the DNA (Deoxyribonucleic Acid) in a blood sample helps the physician to identify carriers.
