CRISPR Gene Editing

"CRISPR/Cas9 has the potential to transform the world; yet, the ethical cloud of human modification overshadows these conversations."

All living organisms contain genes in their cell(s). These genes consist of DNA, which provides instructions to the cells. The DNA is made up of 4 bases- Adenine, Guanine, Thymine, and Cytosine.

With gene editing, scientists can modify and edit these bases based on their requirements. And CRISPR is one of the most popular of these gene-editing tools- due to its price, efficiency, and effectiveness.

CRISPR is a gene sequence found in certain bacteria originating from a bacteriophage (a virus that infects bacteria). It is used to detect and destroy bacteriophages, with the help of acquired immunity.

CRISPR has two components, Clustered Regularly Interspaced Short Palindromic Repeats and Cas (CRISPR associated proteins). The Cas is responsible for cutting the DNA sequence wherever required. When a virus invades a bacteria, the Cas protein cuts a segment of the viral DNA and adds it to the bacterial DNA. These segments are repeated and bind to a protein called Cas-9 which then scour the organism for invaders. If a virus invades again, the RNA-Cas-9 complex detects it and immediately fights it off.

This feature is common to many types of bacteria. But in 2012, scientists had a breakthrough with this mechanism. They figured out how to use this mechanism to target any form of DNA, in any kind of organism.

In the laboratory setting, scientists choose the DNA segment they want to scour for and attach it to the Cas-9 protein. It finds the target and cuts off the required segment. This edits the genome simply and quickly.

When the DNA is cut, the cell tries to repair it with a method called Nonhomologous End Joining. This might cause additional or missing bases, leading to that gene becoming unusable. But there is a solution, Homology Directed Repair. Here, a template DNA is added to guide the repair process.

This technology has several uses. One of the main ones is for curing genetic diseases like sickle celled anaemia. Or to create mosquitoes that cannot act as vectors of malaria. It can also be used in the agricultural industry, to create a product that is appealing to customers.

Although there are benefits, CRISPR also raises ethical questions. The long-term effects of the technology are not yet known. And is it okay to genetically modified organisms? There is also the problem of designer babies, where parents can choose their child's genetic makeup to be.

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