Genomics, gene editing and cell therapy

Prelims and Mains

Epigenetics is heritable change in how active a gene is, without any change to the DNA sequence itself.

• A gene is a stretch of DNA whose sequence of bases spells out one protein.
• 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.

Prelims and Mains

Stem cell therapy treats disease with stem cells, and every proven use replaces a tissue with the same tissue.

• The bone marrow transplant, haematopoietic stem cell transplantation, treats leukaemia, lymphoma, thalassaemia and aplastic anaemia.
• Limbal stem cells from the eye restore a cornea scarred by chemical burns, and cultured skin cells are grafted onto severe burns.
• Other conditions, neurological and degenerative disease among them, remain investigational, for an approved clinical trial only.
• The Central Drugs Standard Control Organisation regulates stem cell products as drugs under the New Drugs and Clinical Trials Rules, 2019, and the National Stem Cell Research Regulation Committee oversees research.

See also: Central licensing of cell and gene therapies

Prelims and Mains

Base editing, developed in 2016, converts one DNA letter into another without cutting both strands, unlike CRISPR-Cas9.

• Because it does not cut both strands, it should cause fewer unintended changes.
• Delivery to the brain needs large doses of adeno associated viruses, which can provoke a severe immune reaction.