The UK Drug Regulator has recently approved a revolutionary gene therapy, known as Casgevy. This marks a turning point in medical history as it’s the first-ever licensed therapy using the CRISPR-Cas9 gene editing technology, which brought its inventors a Nobel Prize in Chemistry in 2020. This progressive therapy offers a significant breakthrough for managing diseases such as sickle cell disease and thalassaemia.
Understanding How Casgevy Therapy Works
Both sickle cell disease and thalassaemia have their roots bind to errors in the gene that’s responsible for haemoglobin—a vital protein found in red blood cells that transports oxygen to different organs and tissues. The Casgevy therapy deploys the patient’s own blood stem cells, which are meticulously edited using CRISPR-Cas9. This therapy is designed to target a gene known as BCL11A, considered crucial in transitioning from foetal to adult haemoglobin.
Interestingly, foetal haemoglobin—which every individual naturally possesses at birth—does not encapsulate the same irregularities as adult haemoglobin does. Hence, the Casgevy therapy enables the body’s native mechanisms to begin generating an increased volume of this foetal haemoglobin, thereby easing the symptoms linked to both conditions.
The Casgevy procedure involves a single treatment where the patient’s blood stem cells are first extracted through a method known as apheresis. These cells are then edited over a span of approximately six months before being reinserted into the patient’s body.
Unpacking Sickle Cell Disease and Thalassaemia
Sickle cell disease is a genetic disorder affecting the blood by causing an abnormality in the hemoglobin protein. As a result, red blood cells assume a sickle or crescent shape, obstructing their mobility through vessels and potentially leading to severe pain, infections, anaemia, and strokes. In India, estimates hold that 30,000-40,000 children are born with sickle cell disease each year.
Thalassaemia, on the other hand, leads to severe anaemia as a result of low haemoglobin levels, thereby requiring lifelong blood transfusions and chelation therapy to manage iron accumulation. Major symptoms include fatigue, paleness or jaundice, shortness of breath, and delayed growth.
Diving Deep into CRISPR-Cas9 Technology
CRISPR-Cas9 is a revolutionary technology that equips geneticists and medical researchers with the capability to alter specific segments of the genome. This is facilitated through precise removal, addition, or alteration of sections within the DNA sequence.
The technology comprises two crucial parts for editing DNA. Firstly, there’s Cas9, which operates like molecular scissors, snipping the DNA at designated spots. Secondly, there’s guide RNA (gRNA), consisting of a specifically designed sequence. This sequence directs Cas9 to the exact position in the genome where the cut needs to be made, ensuring Cas9 functions accurately and allows for distinct changes in the DNA.
Previous UPSC Civil Services Examination Questions
In the 2019 Civil Services Examination, a question asked was – “What is Cas9 protein that is often mentioned in news?” The answer was “(a) A molecular scissors used in targeted gene editing”.
Then in the 2021 examination, another question was asked about the research and developmental achievements in applied biotechnology and how these achievements will help uplift the poorer sections of society.
Gene therapy, especially therapies like Casgevy using CRISPR-Cas9 technology, has opened up innovative treatment avenues for chronic diseases like sickle cell disease and thalassaemia. These scientific advancements bring fresh optimism and hope for patients, suggesting a future where such diseases could potentially be eradicated.
Last Modified: February 22, 2024