The constant growth of technology in recent years has affected all facets of civilization, but many believe that the most important area of life it has affected is the science of medicine. In ancient times, when there were no advanced tools at humans’ disposal, the diagnosis and treatment of a disease was particularly difficult. However, things have now changed for the better.
In fact, if the clinical trials succeed, we will soon be treating patients of muscular dystrophy by editing their genes!
What is Duchenne Muscular Dystrophy?
Duchenne muscular dystrophy is an inherited muscle disorder that affects 1 out of 3600 boys. It involves progressive muscle-weakening that worsens faster than other types of muscular dystrophies (like Becker’s muscular dystrophy). It usually affects boys who have a family history of the disorder, and symptoms begin to appear between the ages of 2 and 3 (although lab testing can identify the disorder at birth).
Boys afflicted by Duchenne muscular dystrophy may need to use a wheelchair by age 10, and are at a high risk of an early death due to difficulties in breathing or heart failure.
What Causes Duchenne Muscular Dystrophy?
The disorder is caused by a mutation (defects) in the gene dystrophin (located on the X-chromosome), which encodes a protein called dystrophin. This protein is a vital part of the muscle tissue that imparts stability and is crucial for proper muscle function.
Although both males and females can carry the mutation in the gene, this disorder rarely affects girls. The son of a girl who ‘carries’ the mutation (or is a ‘carrier’) has a 50% chance of being afflicted by the condition.
Since this condition is hereditary in nature, numerous attempts have been made to cure it through gene therapy. An alternative treatment that’s based on chemicals (antisense oligonucleotides) is presently undergoing clinical trials. Unfortunately, there hadn’t been much success against this condition through gene therapy… until now!
The idea of curing an inherited disease by inserting normal genes into damaged cells is making the news once again, and this time, it looks quite promising. A novel technique, called Crispr-Cas9, lets doctors cut the DNA of chromosomes at selected sites to insert or altogether remove afflicted parts.
Success in Mice
Three research groups, led by three different researchers (including Charles A. Gersbach of Duke University, Eric N. Olson of the University of Texas Southwestern Medical Center and Amy J. Wagers of Harvard University), conducted Crispr-Cas9 tests on mice. Their observations were reported in the journal Science on December 31, 2015, wherein they loaded the DNA-cutting system onto a virus that was intended to infect the mice’s muscle cells.
The system removed a certain defective part from the DNA of the mice; although it did shorten the dystrophin protein, it also resulted in providing more muscle strength to the mice! “This method, if proven safe, could be applied to patients in the foreseeable future,” said Dr. Gersbach, one of the lead researchers in the three research groups.
In the present scenario, it turns out that through gene editing, we have found a permanent cure to treat patients of Duchenne Muscular Dystrophy. What needs to be done now is to scale up the entire process, render it more efficient and ensure (through clinical trials) that the process is safe for use in humans, so that the number of tragic deaths due to this dreadful condition can be curbed.
- Duchenne Muscular Dystrophy – Medline Plus (U.S. National Library of Medicine)
- Learning About Duchenne Muscular Dystrophy – National Human Genome Research Institute (NHGRI)