Muscular Dystrophy

Duchenne's Muscular Dystrophy

First described by the French neurologist Guillaume Benjamin Amand Duchenne in the 1860s Duchenne muscular dystrophy (DMD) is by far the most common form of muscular dystrophy. DMD Accounts for an estimated 50 percent of all cases affecting 1in 3000 to 1 in 4000 births. Current estimates of the total current cases in the United States alone are 15,000 at any given time. The cause of DMD is the complete lack of dystrophin, the protein responsible for keeping muscle cells intact. DMD usually manifests between the ages of 3 and 5. Symptoms include pelvic and leg muscle weakness accompanied by a waddling gait, toe walking, difficulty climbing stairs and scapulae flare. Some individuals with DMD, approximately one third, may have a slight learning disability. A minute percentage of those affected may be mentally retarded as well. Pattern of inheritance, X-link recessive and principally affects males that inherit the gene from the mother. Females may carry the gene but expression is extremely rare.

Progression occurs rapidly and affects all voluntary muscles and eventually involuntary muscles. Those affected usually require a wheelchair between the ages of 9 and 12. Progressive weakness of the cardiac muscles and pulmonary complications result in a life expectancy of twenty years.

Becker's Muscular Dystrophy

Similar to DMD a less severe variant Becker muscular dystrophy (BMD) was described by the German doctor Peter Emil Becker in the 1950s. BMD progression is placid in comparison to DMD. The occurrence of BMD is estimated at one tenth that of Duchenne muscular dystrophy although estimates are as high as 1 in 20,000.

The cause of BMD results from an insufficient production of dystrophin which results from a mutation on the same gene as DMD. The onset of BMD usually occurs in adolescence or early adulthood. Symptoms of BMD are markedly similar to DMD although less severe and more unpredictable. The legs and pelvic area are affected usually less severely. Shoulder muscles are weakened and results in scapulae flare. Affected individuals are usually able to walk well into their thirties and forties. Pattern of inheritance, X-linked recessive and principally affects males that inherit the gene from the mother. Females may carry the gene but expression is extremely rare.

...