Test : Duchenne/Becker Muscular Dystrophy DNA detection
Indications : Genetic testing involves analyzing the DNA to detect a mutation in the dystrophin gene and its exact place of location. Many women act as carriers of the mutated gene and, sometimes, they themselves show symptoms of the disease. The test helps to identify carriers and estimate their chances to pass it on to their children. The test is also done as a prenatal diagnosis in a fetus of carrier parents.
Blood is collected from the patient and the DNA is isolated, fragmented and allowed to run through a gel electrophoresis. Depending on its weight the DNA fragments are spread on the gel. This is then transferred to a special blotting paper, denatured and fixed. This denatured DNA is exposed to fluorescing probes which can then be detected using fluorescent techniques.
Physiology : Duchenne and Becker Muscular Dystrophy is genetic condition that is characterized by muscular wasting (atrophy). It particularly affects the skeletal and cardiac muscles.
A mutation in the Duchenne muscular dystrophy (DMD) gene causes muscular wasting. The DMD gene controls the production and function of the protein dystrophin which helps to stabilize the cardiac and skeletal muscles. Mutations in the DMD gene lead to the dysfunction of the protein, causing the muscles to become weak.
DMD has an X-linked recessive pattern of inheritance. In males a mutation in a single X chromosome they possess is enough to bring on the condition while in females it is necessary for the mutation to be present in both the XX chromosomes.
Interpretation : The presence of mutation in the DMD gene indicates muscular dystrophy. Once the condition is identified treatment can be initiated accordingly. In some, the mutation is present in a single chromosome and this is an indication of carrier status.
Test Method : Polymerase chain reaction and Southern blotting
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