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Article by: Clarice
Among the many emerging medical disciplines that have surfaced in recent years, is genomic medicine. Genomic medicine is a medical discipline that centralises patient care around the genetic information of an individual.
The CRISPR/Cas9 gene editing system that won the Nobel Prize in Chemistry in 2017 is one of the paradigm-shifting discoveries made in the field of genomic medicine by two women, Emmanuelle Charpentier and Jennifer A. Doudna. This technological contribution has allowed scientists to make precise changes in the genetic material of most organisms, including people.
CRISPR is short for Clustered Regularly Interspaced Short Palindromic Repeats and is often aptly described as “genetic scissors” due to its ability to edit segments of DNA. This tool has been used by agriculturists to develop crops that could withstand pests and drought and to improve the immunity of bacteria against viruses in the production of cheese and yoghurt. In medicine, CRISPR is being used in clinical trials of new cancer treatments and to cure certain hereditary diseases.
In the treatment of hereditary diseases like sickle cell anaemia, CRISPR works its magic by altering malignant DNA variants that alter cellular functions, for example, the defective crescent-shaped red blood cells in an individual with sickle-cell anaemia.
DNA variants or mutations have the potential to cause either single-gene disorders (monogenic diseases) or multi-gene disorders (polygenic diseases). Monogenic diseases like sickle-cell anaemia are caused by a DNA variant in a single gene. Meanwhile, polygenic diseases like Type 2 diabetes and schizophrenia are caused by combinations of DNA variants. Interestingly enough, a single DNA variant in a polygenic disease doesn’t cause disease on its own but only does so in combination.
The CRISPR/Cas9 gene editing system facilitates the research and treatment of monogenic and polygenic diseases. To begin with, researchers identify suspected DNA variants that cause disease by adding variants to healthy cells. If a variant causes disease, the healthy cell gets sick or behaves abnormally. Researchers are then able to identify disease-causing DNA variants and remove them.
CRISPR is especially effective in polygenic diseases as researchers can quickly study many DNA variants simultaneously, which was simply infeasible before gene editing. Using this information, researchers can then change disease-causing DNA variants to healthy ones through cell therapy as well as develop more efficacious drugs and treatments.
Take sickle-cell anaemia, for example, which can be cured by cell therapy. Cell therapy involves the use of modified cells to treat a hereditary disease. Cells are isolated from an individual and then genome-edited and multiplied in a laboratory. Then, the modified cells are given back to the patient through intravenous (IV) infusion. In the treatment of sickle-cell anaemia through cell therapy, it is the blood stem cells that are collected and modified.
This mode of treatment has a 90-95% success rate. America’s first CRISPR trial in 2019 yielded impressive results: 22 patients were treated with 100% success. Despite this relatively new tool revolutionising the treatment of diseases in medicine, it goes without a doubt that CRISPR has led to many social, moral, and ethical debates worldwide. It raises hope for those who suffer from diseases once thought to be incurable, as well as a litany of thorny questions. Do the benefits outweigh everything else? What do you think?
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