Mitochondrial replacement therapy (MRT)
What is MRT?
Mitochondrial Replacement Technique (MRT) is a modern medical method developed to help prevent the passing of certain genetic diseases from mother to child. These diseases are caused by problems in the mother’s mitochondrial DNA (mtDNA).
Role of Mitochondria and mtDNA
- Mitochondria are structures within cells that provide energy. They contain their own small amount of DNA, separate from the nuclear DNA. Mutations in mitochondrial DNA can cause various disorders.
Mitochondria (singular: mitochondrion) are tiny structures found in almost all cells of plants, animals, and other living organisms (except bacteria). They are known as the “powerhouses of the cell” because they produce energy for the cell.
Q. In the context of hereditary diseases, consider the following statements: (UPSC 2021)
- Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.
- A child inherits mitochondrial diseases entirely from mother and not from father.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: C
Some mitochondrial diseases are maternally inherited, meaning they are passed from the mother to her children through mitochondrial DNA. These disorders can affect energy production in cells.
- MRT involves replacing defective mitochondria in a woman’s egg with healthy mitochondria from a donor egg. This results in an egg with nuclear DNA from the mother and father and mitochondrial DNA from a donor.
MRT aims to prevent the transmission of mitochondrial diseases to the next generation. It allows couples at risk of passing on such disorders to have genetically related children without the risk of mitochondrial diseases.
“Pronuclear Transfer" technology
“Pronuclear Transfer” technology is a technique used in the context of mitochondrial replacement therapy (MRT) or mitochondrial donation. It is a medical procedure designed to prevent the transmission of mitochondrial diseases from mother to child.
Mitochondrial diseases are genetic disorders caused by defects in the mitochondria, and they are inherited maternally.
The procedure involves the following steps:
- In Vitro Fertilization (IVF): Eggs are collected from both the intended mother (who carries the mitochondrial disease) and a healthy egg donor. Sperm is also collected from the intended father or a sperm donor. In vitro fertilization is performed to create embryos.
- Pronuclear Transfer: After fertilization, but before the embryos start dividing, the pronuclei (nuclei of the sperm and egg) are removed from the embryos of both the intended mother and the egg donor.
- Transfer of Nuclei: The pronuclei from the intended mother’s embryo are discarded, and the healthy donor egg’s pronuclei are replaced with the intended mother’s pronuclei. This results in an embryo with nuclear DNA from the intended parents and mitochondrial DNA from the healthy donor.
- Implantation: The reconstructed embryos are then cultured for a short period before one or more are selected for transfer into the uterus of the intended mother.
