Introduction to gene editing (Part 14- CRISPR in gene editing and beyond)
Welcome to the 14th part of the multi-part series on applications of CRISPR in gene editing and beyond.
Though genome sequencing represents a huge development in the study of genetic disease, it is ultimately a diagnostic tool, not a form of treatment. Undoubtedly genome sequencing allows the researchers to see how genetic diseases are written in the language of DNA, but to cure genetic diseases, the gene itself has to be repaired to permanently reverse the disease-causing mutation rather than just giving drugs to patients to alleviate the adverse effects of the disease temporarily.
Let’s again come to the example of sickle cell disease caused by the mutation in the HBB genes at the seventeenth position, where A is replaced by T nucleotide. Generally, this disease is treated with frequent blood transfusions, the use of the drug hydroxyurea, and bone marrow transplants. But don’t you think it would be better to target the DNA mutation itself that is responsible for causing the disease? Researchers believed that the best solution for treating genetic diseases is to fix the defective gene by rewriting the mutated genetic code.
The technique that aims to treat the genetic disease by rewriting the mutated genetic code is called gene editing or genome editing. For example, gene editing of mutated HBB gene replaces the incorrect T nucleotide at position seventeenth with the correct nucleotide A. The repaired gene translated into amino acids results in the functional beta-globin subunit of the hemoglobin protein. And you know hemoglobin protein is the major oxygen transport component of red blood cells. Thus correcting the sickle cell disease permanently.
Simply put, gene editing or genome editing works in a way similar to Microsoft Word -it’s like using the cursor to correct a typo by removing an incorrect letter and inserting the correct one.
Genome editing inserts, deletes, or removes DNA using artificially engineered nucleases or molecular scissors. There are generally 3 families of artificially engineered nucleases: Zinc Finger nucleases, TALENs, and CRISPR/Cas system, which will be discussed in the following parts.
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