A Promising New Development for Treatment of Duchenne Muscular Dystrophy

Summary: The disease Duchenne Muscular Dystrophy, or DMD, is the most common form of muscular dystrophy. In the class of diseases know as muscular dystrophy, the muscles of the individual break down and eventually die because of the lack of a protein. The protein varies with each type of MD, but in DMD the gene that produces the protein called dystrophin is mutated. Dystrophin normally helps hold the structure of the cytoskeleton of the muscle cells. With DMD, the protein is unable to function because of a missing section of the gene that makes it impossible for the entire protein to connect during translation (protein formation from RNA). However, in the new mouse-tested procedure called exon skipping, a "molecular plaster" is inserted into the genome of the afflicted individual (in this case the mouse) that fills the gap for the missing section, allowing the two parts of the protein to connect. This is called exon skipping because these sections are exons, or coding regions of chromosomes. This procedure does not allow for a complete dystrophin protein to be made though; the individual would still not have the missing exon. This procedure simply allows a partial protein to be made, which makes the symptoms of DMD much milder. The most recent experiments have been more significant than past ones because the tested mice were missing another protein called utrophin, making their disease more severe and therefore closer to what DMD is like in a human.

Connection: This connects to our biology curriculum in a few ways. It connects to our unit on the muscular system because of the functions of dystrophin. The dystrophin protein allow the muscle fibers to keep their structure as the contract, which we learned is through the movement of the action filaments towards each other. The absence of this protein results in a homeostatic imbalance, interrupting the muscular system's ability to move the body. This connect to our past unit on molecular genetics because of the specific function of the so called exon skipping compounds. These compounds, currently being researched by pharmaceutical companies in various countries, contains molecules that fill the gaps created by a missing exon. We learned about exons, introns, and RNA splicing in this unit. We learned that after transcription, the introns, or non-coding regions of the genes, are "cut out" before the mRNA is sent off for translation. DMD result in the failure of the exon pieces to connect after splicing. Finally, this connects to our cellular unit again because of the function of dystrophin. We learned in this unit about the cytoskeleton and its function in cells. The functions of the cytoskeleton include maintaining the shape of the cell and providing "tracks" on which the organelles can move


URL: http://mda.org/quest/promising-new-development-treatment-duchenne-muscular-dystrophy