Medical researchers are continually on the lookout for new treatments for muscular dystrophy (MD), a group of hereditary muscle wasting diseases that in some cases, shorten life expectancy. There is currently no cure for MD and the treatments are limited to steroidal drugs, physical therapy, surgery and mobility aids to increase the sufferer’s independence.
Now, geneticists have discovered ways in which to skip over the faulty genetic code that causes MD, in order to halt the progression of the disease. This is called exon skipping.
What are Exons?
Genes are made up of two sections called exons and introns. The exons contain information with which to produce proteins that are essential to our bodies. The introns are cut out during the process of protein production, leaving only the exons.
The exons must join up like pieces of a puzzle. If an exon is missing, then the puzzle cannot be completed. The exon will not join on to the next available exon. If a section is missing, it will simply fail to create the rest of the section. Since the muscle protein dystrophin needs both ends of the protein in order to be made, this results in muscular dystrophy.
Now scientists have found a way to "skip over" the missing sections of DNA to join up the puzzle and potentially halt MD.
They can do this by putting a tiny fragment of DNA called an antisense oligonucleotide (AO) over the missing section so that the body will ignore that missing part and skip on to the next part of the DNA, creating an end in the structure that allows dystrophin to be formed.
Can Exon Skipping Help Cure MD?
It is too early to say whether exon skipping will lead to a cure for muscular dystrophy. However, a very small trial involving 19 boys with Duchenne muscular dystrophy has shown promising results. All 19 boys were given intravenous drips of the antisense oligonucleotide (AO) molecular patch over a period of 12 weeks. The boys were divided into groups and each group received a different dosage ranging from 0.5 to 20 mg.
Eight boys who had received the two highest dosages showed that they were consistently skipping exon 51 – the missing exon responsible for Duchenne muscular dystrophy, which was evidence that the molecular patch worked.
Three of the boys also developed 15 percent, 21 percent and more than 50 percent more muscle protein than they had prior to the treatment. Not all of the three were in a high dose group so a little of the treatment may have just as much effect as a lot.
None of the boys experienced significant side-effects and none had any immune system reaction to the therapy, allowing hope that it could be used as a treatment for MD, or one day even a cure.
Source: Muscular Dystrophy Campaign, 4th June 2010.
Joanna is a freelance health writer for The Mother magazine and Suite 101 with a column on infertility, http://infertility.suite101.com/. She is author of the book, 'Breast Milk: A Natural Immunisation,' and co-author of an educational resource on disabled parenting, in addition to running a charity for people damaged by vaccines or medical mistakes.