In 2021, India approved a five-year project to develop CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technology to cure sickle cell anaemia. This marks the first time that India is targeting a disease for therapy using CRISPR-based technology. The project is still in its pre-clinical phase and involves testing on animal subjects.
Understanding CRISPR Technology
CRISPR is a gene editing technology which emulates natural defence mechanisms in bacteria to combat viruses. It does this using a protein called Cas9. Instead of introducing new genes, it either suppresses or modifies existing ones, a process known as genetic engineering. CRISPR-Cas9 is often compared to ‘genetic scissors’, likened to ‘cut-copy-paste’, or ‘find-replace’ functionalities found in computer programs. A faulty stretch of DNA sequence causing the disease or disorder is located, cut out, and then replaced with a correct sequence. CRISPR replicates a natural defence mechanism in certain bacteria that use a similar method to protect themselves from viral attacks.
Mechanism of CRISPR
The mechanism involves identifying a specific sequence of genes causing the problem. An RNA molecule is programmed to locate this sequence on the DNA strand. The Cas9 is then used to break the DNA strand at specific points to remove the harmful sequence. A DNA strand tends to reattach and heal itself when broken. This auto-repair mechanism has to be interrupted by scientists who introduce the correct sequence of genetic codes to the DNA strand. This process is programmable, highly efficient but not completely error-free.
CRISPR Therapy: Significance & Specificity
CRISPR-based therapeutic solutions aim to provide disease treatment right at the root cause by rectifying the underlying genetic error. Specific cells are extracted from patients, gene edited in labs, and then re-injected into the patients, thus offering a specific solution for each disease or disorder. These solutions could be particular to certain populations or racial groups, as genetic factors also influence them. Notably, these changes remain with the individual and do not pass on to subsequent generations.
CRISPR: A Potential Permanent Cure for Genetic Diseases
A wide variety of diseases and disorders, such as sickle cell anaemia, certain types of cancer, diabetes and heart diseases among others, are genetic in nature, implying that they arise from unwanted changes or mutations in genes. CRISPR presents the potential to permanently cure these genetic diseases by detecting and correcting these anomalies at the DNA level.
The Ethical Dilemma Surrounding CRISPR
The power of CRISPR technology to bring about substantial changes in an individual can be misused. In 2018, a Chinese researcher disclosed that he had used CRISPR to alter twin girls’ genetic makeup. This stirred a lot of controversy in the scientific community. Moreover, because of its not completely precise nature, CRISPR might inadvertently alter other genes, which could be inherited by future generations.
Understanding Sickle Cell Anaemia
Sickle cell anaemia is an inherited blood disease prevalent among people of African, Arabian and Indian origin. This disorder affects hemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. Those afflicted have atypical hemoglobin molecules called hemoglobin S, distorting red blood cells into a sickle-like shape. This blocks blood flow and prevents oxygen from reaching all parts of the body. Symptoms include severe pain, often referred to as sickle cell crises, and long-term organ damage. Treatments can include medication, blood transfusions, and in rare instances, a bone-marrow transplant.
Previous Year Questions on CRISPR in UPSC Civil Services Examination
In the 2019 UPSC Civil Service Preliminary examination, a question was asked about the Cas9 protein. The question was, “What is Cas9 protein that is often mentioned in news?” and the correct answer was, “A molecular scissors used in targeted gene editing”. A mains question was also asked about the research and developmental achievements in applied biotechnology and their potential to uplift the poorer sections of society.
