CRISPR Could be the Possible Cure for Muscular Dystrophy

How about technology that could offer a “cut and paste” or just a “delete” solution to all genetic mutations, defects, and resulting disorders? Well, that may sound too much to ask for, an oversimplification, but it is exactly what many scientific researchers in the field of genetic modeling are promising.

For decades, science has been busy identifying the various genes and resultant health problems. With the improvement in the genome decoding and power of computing, it is becoming possible to dig deeper into the subject. But still, all the genetic studies provide better insight into the problem. To date, medicine has not made much success in delivering the promise of changing things at the genetic level, without causing someone any harm.

The problem is graver than we may think. Our genes not only mutate, but they may have foreign genetic material implanted by infections. Think of a viral infection like HIV, modern drug therapy can suppress the infection to almost zero levels in the blood. Yet, it survives by implanting its genetic code inside DNA, making it completely helpless. This is how many viruses reside inside the body. But here is a hint too, if a certain microorganism can edit their gene code, so can humans, at least in theory.

There are different kinds of muscular dystrophies. They are either caused by inheritance of defective gene, or due to spontaneous mutation of the gene. These defective or mutant genes cannot produce the right kind of chemicals required by our muscles. Thus muscles start to die.

Worst of all these diseases usually start at a young age, and at present, there is no cure for them. Most of the medicine is targeted at slowing down the disease process and controlling the symptoms.

But now finally we can see the ray of hope on the horizon, as genetic code editing is gaining momentum and becoming a precise science. This is where the CRISPR comes into the picture.

What is CRISPR?

It is a short form for Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR). This is a technique or strategy that bacteria use to defend themselves from the viral attack. They do it by keeping the copy of the viral genome in their own gene, so that when the next time the same kind of virus attacks, they are able to kill it by identifying the genetic material of the virus and destroying it through editing.

Scientists have learned to use this methodology in laboratory conditions. This gave scientists a tool for copying and pasting genetic materials. An editing tool they have been looking for. Though it has demonstrated its accuracy in the animal models, however, it is still not being used in humans. The reason is that the human genome is far more complicated, and there is no scope for the mistake. Thus scientists have to be absolutely sure about their actions.

Could CRISPR be the cure for muscular dystrophy

We have reasons for being confident about it. As technology is already showing some very good results in animal models.

In one of the experiments, scientists edited the genetic code of the mice that had a rare kind of muscular dystrophy. After the changes in genetic information, the mice made a complete recovery.

In muscular dystrophy, there is a progressive loss of muscle cells due to genes that are not able to provide the right code from some construction materials for muscles. Thus if a certain technology is able to modify the genetic code (by removing the malicious code) even in 15-20% of muscle cells, that is enough for the recovery.

In humans, the main target for such gene therapy is the Duchenne muscular dystrophy. Reason being that it is the most common of all. The majority of people suffering from debilitating muscular dystrophy are known to have Duchenne’s disease. It is the disease of young males. Malicious or mutant genetic code that causes this disease is more or less well recognized by science. Thus the hope is to simply replace the unhealthy gene with the right kind of code.

CRISPR technology is still very young, but in the few years of its existence, it has taken the world of gene modification by storm. There is huge enthusiasm among the various scientific communities. In fact, some of the startups have already collected a huge amount of funds for helping the future beneficiaries of this technology.

The question that arises is now that why science has not yet started treating humans if they have good results in animals. Well, the reason is that no one can say for sure that they know about all the genes that cause Duchenne’s disease. Medicine knows very well that such a kind of disorder is often caused by a combination of several mutant or wrong genetic codes rather than some small single sequence of code. Therefore, a reason for doubt that making changes at a few known places would work in practice.

Further, things are made complicated by the fact that single diseases like Duchenne’s may have a different combination of defective gene sequences in various individuals. Treatment that worked in one person would not essentially work in another person. This means that treatment has to be individualized.

Another reason for worry is that this is still very new territory. No one can say for sure about the long-term implications of such gene editing. No one can guarantee that CRISPR would do exactly what the scientists or doctors want it to do. It may cause changes in some other parts of the genes too, that may cause other non-curable ailments.

Albeit all the worries and skepticism, we have many reasons for optimism. This method has provided us the tools for gene editing. Moreover, results in animals are very encouraging. Thus, it is just a matter of time before the experiments in humans begin. Doctors and scientists just want to make sure that before any such intervention on humans they have the maximum information at hand, and that the technology is well-refined.

This technology has huge perspectives in providing individualized medicine. The role is not only limited to genetic diseases. In the future, it will open doors for treating cancers, infectious diseases, making every other possible change in the genetic code for our long and healthy life.

References 

A CRISPR Solution to Eliminating Muscular Dystrophy | Stories [Internet]. PerkinElmer. [cited 2017 Sep 18]. Available from: http://www.perkinelmer.co.uk/corporate/stories/crispr-eliminating-muscular-dystrophy.html 

CRISPR: A game-changing genetic engineering technique [Internet]. Science in the News. 2014 [cited 2017 Sep 22]. Available from: http://sitn.hms.harvard.edu/flash/2014/crispr-a-game-changing-genetic-engineering-technique/

Sander JD, Joung JK. CRISPR-Cas systems for editing, regulating and targeting genomes. Nat Biotech. 2014 Apr;32(4):347–55.

Hoeven D van der. Duchenne muscular dystrophy CRISPR cure: just for the rich and well-connected? [Internet]. Bio-Based Press. 2017 [cited 2017 Sep 18]. Available from: https://www.biobasedpress.eu/2017/05/duchenne-muscular-dystrophy-crispr-cure-just-rich-well-connected/