Vast number of patients suffering from lifelong incurable diseases such as Sickle cell disease , Cystic fibrosis or Haemophilia and many more are at the threshold for a complete reversal of the disease and in near future shall influence favourably the treatment of poorly treated cancer , heart diseases and even mental illness .
Thanks to this newly acquired genome editing tool which can cut copy and paste the diseased genes with a healthy counterpart very effectively. This is known as CRISPR cas 9 , a Genetic editing tool ,short for Clustered Regularly Interspersed Short Palindromic Repeats and associated protein 9 ,discovered by two brilliant lady scientists CARPENTIER & DUODNA, which brought them the coveted Nobel prize for chemistry 2020.
CRISPR cas 9 system consists of two key molecules that introduce a change or alter the strand of DNA (Deoxyribonucleic Acid) within a genome (chemical basis of inheritance):
1. There is cas 9 enzyme, a nuclease protein which acts just like a molecular scissor . It cuts the strands of double stranded DNA at a specific location at both ends so that a segment of desired DNA can be removed
2. A ‘guide ‘ RNA (Ribonucleic Acid) a pre designed segment of about 20 bases long , is located within a longer RNA scaffold. This scaffold binds to DNA to which it is complementary and this pre designated sequence guides CAS 9 to the specific part of the genome where it cleaves the DNA at specific location with perfect 100 % precision .
By doing so this combination of CAS 9 and guide RNA knockdown the diseased DNA within a genome following which either the cut ends join and produce a changed unstable DNA or another appropriate DNA made out of suitable complementary RNA is inserted to rectify the defective genome and bridge the gap .
The idea of CRISPR CAS 9 system is the result of understanding the Bacteriophage system. Bacteriophage is a Virus which attacks the bacteria and in the process allows a part of its viral genes in the form of DNA to be attached to the bacterial nucleus. When challenged by the virus again they take help of their inherent CRISPR cas 9 system makes a guide RNA copy of the previous viral genome DNA and cleaves the corresponding invading viral genome with the help of CAS 9 Just like a scissor.
Such exercise of cutting the parts of genes and replacing it with other sets of healthy desired genes can be either of embryonic cells ( sperm or ova in humans ) or of somatic cells ( derived cells which compose different body parts such as heart or lung etc ). The changes brought in somatic nucleus will be limited for only that person or organism but changes created in embryonic nucleus will make changes for successive generations of cells also and therefore it may open a pandora’s box of scientific and ethical possibilities which can produce demon or God with the help of this genetic tool of immense importance .
Considering its far reaching consequences for mankind and the whole biosphere the use of this genetic engineering tool needs to be properly regulated at international level much like we have atomic energy regulatory bodies. It’s use should only be for alleviating the sufferings of mankind and nothing beyond.. The choice is ours because the consequences are even beyond human imagination as shown in blockbuster movies such as Jurassic park, Jurassic world or more recently Rampage by Brad Payton (2018) and Human Nature by Adam Bolt in 2019!
The Author is Currently Professor of medicine at Manipal Tata Medical College and Formerly Professor and Head, Department of Medicine at Rajendra Institute of Medical Sciences, Ranchi, Jharkhand.