Gene Therapy - Shifa Malik

Have you ever wondered what medical conditions like Down syndrome or cystic fibrosis have in common? They’re both caused by genetic mutations, "errors" in the human body.

A gene is what controls your physical characteristics and the way your body functions. Genes are made of DNA, a chemical that contains the ‘code’, or the instructions, of how your body develops and functions. A genetic disorder (like the ones mentioned above) occurs when a protein that forms a gene is not folded properly, or when an error is made as genes are passed down from parent to child. An example of this is what could happen when the TP53 gene is mutated. This gene codes for a protein (p53) which regulates the cell cycle, which generates new cells through cell division. Therefore, p53 controls the rate of tumor growth, because a tumor is formed when a damaged cell continues to divide. The p53 protein isn’t able to destroy the DNA this damaged cell contains like it’s normally supposed to because the TP53 gene isn’t working properly due to a mutation. Therefore, this damaged cell could go from one to an abnormally large mass of cells. Since this gene is mutated, it actually accelerates the growth of a tumor. This small genetic mutation that damages one protein is among many others that are the cause of over 6,000 genetic disorders!

There are many various kinds of mutations that exist. Some of the ones that are more straightforward to understand are insertions, where a piece of DNA is added to the gene, or deletions, where a piece of DNA is removed. Some mutations can block a normal protein from carrying out its duties, or turn a gene ‘off’, which means it’s not expressed and not carrying out any of the instructions that the DNA provides, when it’s supposed to be on. They can also be classified as either hereditary, which means it was passed down from a parent through an egg or sperm cell, or acquired (somatic), which can be caused by environmental factors, such as prolonged exposure to the sun, smoking, or radiation. There are also harmless mutations of DNA called polymorphisms that are the reason for certain eye or hair colors that are different from the rest of the individual’s family . However, polymorphisms can also affect the risks of developing certain disorders.

You might be wondering, is there a way to prevent mutations? Well, kind of - but it’s still new and pretty rare. According to the National Institute of Health, gene therapy is when a mutated gene is replaced, repaired, or controlling how much of it is “turned on.” This can be done through a vector, which is injected into a specific tissue of the body. A vector carries the normal gene to a specific location. Modified viruses are used as vectors because they can infect the cell that needs the gene with no harm. Currently, this type of therapy is only being used for diseases that have no other cure. One technique of gene therapy called Spliceosome-Mediated RNA Trans-splicing, SMaRT for short, targets and repairs specific sequences of messenger RNA (mRNA) transcripts that contain the mutation with enzymes. Another technique known as gene silencing can turn a faulty gene ‘off’ so that it can’t produce proteins. Additionally, researchers are finding a way to use a patient's immune system to fix mutations. They found that by isolating a white blood cell that attacks antigens, which are threats to the body, they can engineer them to target a specific antigen so that when the cell is reintroduced to the body, it can destroy any cell that carries the antigen.

So what’s next? There have been a number of gene therapy drugs that have been proven to be safe for use, but they’re very costly, and there’s been some hesitation about using them. This article is updated every 6 months with gene therapies that are approved and tested along with their dose and cost. Hopefully, one day there can be a world where gene mutations can be prevented before they cause any permanent damage.

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