From UPSC perspective, the following things are important :
Prelims level : Base Editing
Mains level : Not Much
A teenage cancer patient suffering from T-cell acute lymphoblastic leukaemia (T-ALL) has defeated her seemingly incurable cancer with the help of base editing technique.
- Bases are the language of life. The four types of base – adenine (A), cytosine (C), guanine (G) and thymine (T) – are the building blocks of our genetic code.
- Just as letters in the alphabet spell out words that carry meaning, the billions of bases in our DNA spell out the instruction manual for our body.
- Base editing allows scientists to zoom to a precise part of the genetic code and then alter the molecular structure of just one base, converting it into another and changing the genetic instructions.
- The large team of doctors and scientists used this tool to engineer a new type of T-cell that was capable of hunting down and killing cancerous T-cells.
What is T-Cell?
- T (thymus) cells are type of white blood cell.
- They are part of the immune system and develop from stem cells in the bone marrow.
- They help protect the body from infection and may help fight cancer.
- Also called T lymphocyte and thymocyte.
How base editing helped this teenage cancer patient?
- Doctors started with healthy T-cells that came from a donor and set about modifying them.
- The first base edit disabled the T-cells targeting mechanism so they would not assault patient’s body.
- The second removed a chemical marking, called CD7, which is on all T-cells.
- The third edit was an invisibility cloak that prevented the cells being killed by a chemotherapy drug.
- The final stage of genetic modification instructed the T-cells to go hunting for anything with the CD7 marking on it so that it would destroy every T-cell in patient’s body – including the cancerous ones.
- That’s why this marking has to be removed from the therapy – otherwise it would just destroy itself.
- If the therapy works, the patient’s immune system – including T-cells – will be rebuilt with the second bone-marrow transplant.