Genomics, gene editing and cell therapy

Prelims and Mains

A gene is a stretch of DNA whose sequence of bases spells out one protein, and Mendel's rules have each of its two copies passed on unchanged and independently. A map of the chemical marks carried on the DNA of two mouse strains has now turned up more than 500 instances of inheritance those rules do not predict.

• A gene is felt only when it is read: transcription copies it into messenger ribonucleic acid (mRNA), and translation builds the protein from that copy.
• The marks mapped were DNA methylation, read across the two strains by nanopore sequencing.
• In some regions the methylation depended on the mouse's sex.
• Marks could copy from one gene copy to the other.
• Similar mechanisms may explain human conditions that resist standard genetic analysis.

Prelims and Mains

Every proven use replaces a tissue with the same tissue, and each took decades of trials to reach the clinic. The list is short, and a good deal shorter than what clinics advertise.

• Haematopoietic stem cell transplantation, the bone marrow transplant, treats leukaemia, lymphoma, thalassaemia and aplastic anaemia.
• Limbal stem cells from the eye restore a cornea scarred by chemical burns.
• Cultured skin cells are grafted onto severe burns.
• Other conditions, neurological and degenerative disease among them, remain investigational, for an approved clinical trial only.
• No whole organ has yet been grown from stem cells for human transplant.

Prelims and Mains

Research and the products sold as treatment fall to different regulators. The newest guidelines are a layer added on top of that division rather than a replacement for it.

• The National Stem Cell Research Regulation Committee oversees research using minimally manipulated stem cells.
• The Central Drugs Standard Control Organisation (CDSCO) regulates stem cell products as drugs, under the New Drugs and Clinical Trials Rules, 2019.
• The Health Ministry's Centre for Evidence Based Guidelines issued guidelines on stem cell therapy and regenerative medicine for 2025 to 2026.
• They join the National Guidelines for Stem Cell Research 2017, the gene therapy guidelines 2019, the haematopoietic cell transplantation guidelines 2021 and the cord blood banking guidelines 2023.
• India's first in human gene therapy trial was run by the Centre for Stem Cell Research with Christian Medical College, Vellore.