Gene therapy

15 Dec 2022 Gene therapy

Posted at 11:46h in Daily current-affairs by sharad 0 Comments

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Significance for Prelims: Concept of ‘ base editing’, CRISPR-cas 9 system

Significance for Mains: Advancement of New Technology.

News: New cancer therapy developed by Scientists from United Kingdom recently reported success in a teenaged girl, Alyssia.

About T-cell acute lymphoblastic leukaemia cancer:

T-cell acute lymphoblastic leukaemia cancer disease is a rapid and progressive
This is a form of blood cancer where T-cells turn against the body.
When T-cell turn against the body it end up destroying healthy cells.
Usual treatment of T-cell acute lymphoblastic leukaemia cancer: Chemotherapy and radiation therapy.

Recently a girl named Alyssia, who has the form of cancer called T-cell acute lymphoblastic leukaemia was treated with a new form of cancer therapy.

Alyssia’s treatment: Various standard treatments, such as chemotherapy and radiation on Alyssia, 13, met with limited success. After that, she was enrolled in the trial testing of experimental medicine. Doctors and scientists from the University College, London and Great Ormond Street Hospital gave gene therapy to Alyssia therapy based on a new technique called ‘base editing. In the case of Alyssia’s T-cells, because of mix arrangement in the sequence of bases had become cancerous.

Base-editing for Alyssia’s therapy:

Objective of the gene therapy was to treat T-cell leukamia by fixing her immune system in such way that it stops making cancerous T-cells.
First Step: Extraction of Healthy T-cells were from a donor and then put through a series of edits.
Second Step: Editing of first base blocked the T-cells targeting mechanism to stop it from attacking Alyssa’s body, the second base removed CD7 chemical marking which is on all T-cells and the third base prevented the killing of cells by a chemotherapy drug.
Third Step: T-cells were programmed to destroy all cells whether it is cancerous or protective with CD7 marked on it.
Final Step: After spending a month in remission,Alyssia was given a second donor transplant to regrow her immune system with healthy T-cells.

Concept of ‘ base editing’:

Genetic code of person is various permutations of four bases i.e. Adenine (A), Guanin (G), cytosine (C) and thymine (T).
Sequences of these bases are akin to letters in the alphabet. In various types of cancer, it happens due to mis-arrangement in the sequence of bases. For healthier immune system this mis-arrangement needs to be corrected. Advancement in biomedical engineering technique now allows genes to be altered and errors ‘fixed.’CRISPR-cas9 system is the most popular among these approaches.
Base editing is still a nascent technology, more effective at treating blood disorders caused by so-called single point mutations, or due to change in a single base pair that can cause terminal disease.

Key Facts:

Genes are instructions to produce the wide array of proteins necessary for the body’s functions.
T-Cells are a class of white blood cells equipped to hunt and neutralise threats to the body. T-Cells help in immunity.

About CRISPR-Cas 9 system:

This system is inspired by the defence mechanism of bacteria against viruses.CRISPR-Cas 9 system consists of an enzyme that acts like molecular scissors that help snip out and store pieces of their genes. It can cut a piece of DNA at a precise location and guide RNA to insert a changed genetic code at the sites of the incision. CRISPR-cas9 system is a fast, most versatile system of gene editing.
Improvisation by David Liu of the Broad Institute, Massachusetts on CRISPR-cas9 system: Now, the CRISPR-cas9 system can directly change certain bases: a C can be changed into a G and T into an A.

Source: The Hindu

Article: Explained | How gene therapy could cure cancer

Article Link: https://www.thehindu.com/sci-tech/health/explained-how-gene-therapy-could-cure-cancer/article66264167.ece