So how does all of this macromolecule stuff relate to Muscular Dystrophy?
You have seen that muscular dystrophy is a genetic disease. That means that there is a problem with some gene in people with MD. Genes are in your DNA, which is a nucleic acid. As we keep going this semester, you will see exactly what a gene is, and how a gene can be messed up.
But you have also begun to learn that one of the functions of our DNA (at the bottom of the nucleic acid page) is to make proteins. In fact, each gene that we have is a code that tells us what protein to make. So, in a genetic disease, when a gene is messed up, that means that the person with the genetic disease cannot make a particular protein.
In the case of muscular dystrophy, you have been seeing that some very specific proteins are either not made or are made incorrectly. For example, in Duchenne's & Becker's MD, the protein dystrophin is not right. In Duchenne's MD, the protein is usually not made at all or made really incorrectly. In Becker's MD, the protein is made improperly, but usually has a little function. The protein dystrophin normally works in muscle cells to attach the internal contractile machinery to the cell membrane of the muscle cell. So dystrophin normally acts as a kind of glue, holding these two items together. When dystrophin is absent, there is no glue, and the muscle cannot function. When dystrophin is a little messed up, the glue is somewhat sticky, and some muscle contraction is possible. I used the idea of glue here because I think everyone is familiar with situations where one needs different strengths of glue. Sometimes Elmer's glue will do the job, and other times Krazy Glue is necessary. So imagine that dystrophin is like Krazy Glue. In Duchenne's MD, the muscles need this glue, but don't have any. And in Becker's MD, the muscles need Krazy Glue, but only have Elmer's glue.
Can you believe that a person with a severe problem with just this one protein can end up having to be confined to a wheelchair by 12 years of age? Or that this person will probably die in their 20s?
Understanding the general idea of needing all of our proteins to work properly should help you understand why a genetic disease can be so problematic. Keep in mind that some proteins are really critical for our livelihood!
© 2006 STCC Foundation Press, content by Dawn A. Tamarkin, Ph.D.
Last changed: January 21, 2007