CRISPR: How Gene Editing is Changing Lives
From treating liver disease to preventing the mutation for sickle cell, the gene-editing method known as CRISPR is changing our future.
Staying active is vital towards a healthy lifestyle, right? Well, this simple method is able to prevent many health issues, but Patrick Doherty, an active 65-year-old man, was shocked when his daily walks suddenly became too tiring. Following this, he noticed that his fingers and toes felt pins and needles. Suspecting a deeper issue, he decided to check his symptoms with his doctor. Doherty’s doctor informed him that he had an inherited disease known as transthyretin amyloidosis.
Luckily, gene editing trials for liver diseases such as this were conducted around the time of his diagnosis. Specifically, the CRISPR-Cas9 enzyme would be used to aid in his treatment. Within weeks of this treatment, Doherty started to feel much better. While his recovery was miraculous in and of itself, the data conducted from the experiment is more significant. This gene-editing method could be used for future treatments in a large variety of diseases.
CRISPR-Cas9 has been used to treat many medical issues since its initial discovery. From liver diseases to treating sickle cell anemia, CRISPR’s applications have shown to be near limitless. So how exactly does this method work, and what exactly is CRISPR-Cas9? Let’s take a closer look into CRISPR and discover the components of this life-changing method.
What is CRISPR-Cas9 Exactly?
CRISPR stands for “Clustered Regularly Interspaced Short Palindromic Repeats”. This simply refers to a specific DNA sequence found in the genome of prokaryotic organisms. Remember that prokaryotic organism refers to single-cell organisms such as bacteria and archaea. These DNA sequences were the inspiration for the gene editing method.
Naturally, CRISPR sequences are used by bacteria to protect against viruses. CRISPR sequences are used to “remember” specific viruses, and then it releases an enzyme known as Cas9 is used to “cut” the DNA of the virus, essentially disabling it.
CRISPR-Cas9 refers to the method in which the CRISPR component of the method acts as a homing device for the molecular scissors portrayed by the Cas9 enzyme. In short, CRISPR is used to locate specific DNA sequences, and Cas9 acts as scissors to cut sections of the DNA. The specific process is a little more complex, so here is a visual. Think of CRISPR as a mugshot, it is used to identify a section of the DNA that is targeted. After CRISPR guides the Cas9 enzyme to this location, Cas9 unzips the double helix DNA. Following this, Cas9 then cuts a small section which can then be changed to the scientist’s choosing. This method is highly accurate and efficient.
Applications of CRISPR
So far, we have observed how CRISPR works in gene editing as well as its functions in treating or curing diseases. However, CRISPR also plays an important role in the field of genome research.
Remember how CRISPR-Cas9 is used to unzip the DNA and cut a certain section? Our body, when it senses damage or an irregularity towards its initial form, it attempts to repair this irregularity. Well, how does the DNA strand zip back up and repair its damage? If you thought that CRISPR-Cas9 would fix it back up, you would be incorrect. That would be like trying to glue pieces of paper together using scissors, it doesn’t make sense. Instead, the body attempts to glue the DNA back together using its own processes. This process is often messy and inaccurate, resulting in a variety of outcomes.
The first and most common outcome of the body’s repair process is the disabling of a gene. This may seem like an unfavorable and even dangerous outcome, but there is a lot to learn from this. Comparing a normal cell to another with a disabled gene allows for researchers to gain an understanding of the significance and function of each gene. In this process, the gene might mutate rather than get disabled. This mutation allows for a similar application in which it can be compared to a normal cell to discover the significance of the gene.
The second and less common outcome is that the cell might fix a prior mutation or even insert a completely new gene. Comparing the various outcomes of the DNA repair can help discover further uses of the CRISPR-Cas9 method.
Applications of CRISPR-Cas9 also range far beyond treating diseases and researching genes. CRISPR-Cas9 is also used in applications such as genetically modified food. Specifically, it allows for crops to increase their nutritional value in conjunction with making crops more resistant to diseases and other unsavory factors which can prohibit their growth.
Gene editing with CRISPR-Cas9 is far from perfect, and ethical considerations need to be made before applying this method in humans.
While in many cases CRISPR can be revolutionary, the CRISPR-Cas9 method still has many flaws. For example, we have previously touched on the fact that the Cas9 enzyme can only unzip and cut a portion of a genome. The body will however try to repair itself and many imperfections start here. While the various outcomes of the repair are useful for research, they can lead to larger issues if an unwanted outcome arises. This can be anything from disabling an important genome to creating a harmful mutation. While these issues still exist, scientists actively research the outcomes in hopes of finding a more predictable pattern. Maybe in the future, CRISPR will be closer to the perfect, miraculous technique that we imagine.
Something you might have heard about the use of gene editing in embryos. This allows scientists to control an unborn child’s genetic features. For example, say that a child is more likely to get brown hair and blue eyes, a scientist can alter the genes in the embryo so that the child can have blonde hair and brown eyes. Controlling features of a child raises ethical concerns. As of now, scientists have agreed that that gene editing should not be used for such reproductive purposes. This is for a variety of reasons including concerns for safety, equity, consent, and more.
Want to learn more about CRISPR-Cas9 and gene editing? Check out these websites:
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