Using genetics for therapy
If you are a big science fiction fan, you must have seen movies like X-men or Gattaca. Although fiction, these movies are based on concepts like genetic engineering and mutations. I am sure you might have come across articles about genetic engineering, cloning, etc. Are you wondering if this might bring upon an era of mutants? If you are thinking that then hold your thoughts. We are not talking about genetically engineering human mutants here. We are talking about how genetic engineering could be used as a tool to treat many incurable genetic disorders. Without further ado, let us dive into how genetic disorders are caused and why genetic engineering is such a powerful tool.
It is a known fact that we humans are made up of billions and billions of cells. These cells contain our genetic material known as the deoxyribonucleic acid, or commonly called DNA. Like computer codes, DNA has four basic molecules — adenine [A], guanine [G], cytosine [C], and thymine [T] — arranged in random sequences which make up our genetic material. DNA contains segments of these four molecule sequences called genes. Like in a computer, where the written codes are read to perform a specific function by the computer, our genes are read to make proteins that perform specific functions of the cell. From when we are a tiny embryo in our mother’s womb, the cells are replicating constantly to form the organism that we are. In this replication process, DNA is also copied many, many times. Since we are biological beings and not supercomputers, our replication system, in due course of time, makes mistakes in copying DNA and this leads to what we call mutations. The genetic material is passed on from one generation to another and sometimes so are the mutations. These mutations may have no effect in some cases, but in some others, they may change the function of a protein and hence the function of the cell. This leads to diseases, also called genetic disorders that most often are incurable. Or at least this was the case until recent times.
So how was this achieved? Have you heard of the term gene therapy? Of course, you have. Research in gene therapy has been ongoing for more than two decades, but it has only in recent times gained such public attention. Gene therapy is quite a unique technique that uses the patient’s own genetic material to treat diseases. Gene therapy introduces the corrected genetic material into cells to replace the faulty gene and restore the respective protein’s function. The genetic material requires to be integrated into the patient’s genetic material and if it is delivered directly it would not function. So how can you make the corrected genetic material integrate with the patient’s DNA? Difficult question? Ok, let me tell you how. By using carriers. You might be thinking “but which carriers would help with this integration?” Well, the answer to that is also very simple — Viruses. Are you rereading the line? Do not fret my friends, because you have read it absolutely right — Viruses.
We all know of viruses as the enemy, causing hordes of diseases like influenza, measles, mumps, HIV, sometimes even cancer — the list goes on. Viruses are nasty little things that cannot survive on their own. So when they find a living host, here let’s say a cell from our body, they latch on to it much like a parasite and enter the cell. Once they enter the cell, they replicate themselves and start infecting other cells, killing these poor cells along their way. Some viruses are also capable of integrating their genetic material into our DNA. Indeed, viruses can be a devil sometimes, but our clever scientists found a way to use these infecting properties to their advantage. They decided to remove the genetic material from the viruses, which leaves only the empty shell — “a carrier.” The corrected genetic material can be inserted into these shells and delivered to the patients. These vectors can be delivered to the cells in two ways — one by direct injection of vectors to the specific tissue or in the blood (in vivo gene therapy) or by removing cells out of the body to deliver the vectors and then injecting the cells back to the patients (ex vivo therapy). Other vectors have been used to deliver the correct genetic material, however, the most efficient and successful vectors so far have been viruses.
The very first gene therapy was used to treat ADA-SCID (also known as bubble boy disease) in the early 2000s. Patients affected by ADA-SCID have a non-functional immune system and are susceptible to all kinds of infections. There have been various clinical trials and some very unfortunate failures since then. But in recent times with advances in research gene therapy has been developing its full potential and achieving quite some success. So does that mean we have found the cure for all the genetic disorders? The current answer to that question is sadly ‘no’. There is still a long way to go before scientists achieve the impossible but what can be said for sure is that we are moving in the right direction.
To know more about these successful stories check out: https://www.technologyreview.com/s/609643/2017-was-the-year-of-gene-therapy-breakthroughs/.
