In the context of hereditary diseases, consider the following statements:
- 1.Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.
- 2.A child inherits mitochondrial diseases entirely from mother and not from father.
Which of the statements given above is/are correct?
Answer & explanation
Answer: (c) Both 1 and 2
Both statements are correct: mitochondrial DNA comes only from the mother's egg, and mitochondrial replacement therapy swaps the faulty mitochondria either before fertilisation (spindle transfer) or after it (pronuclear transfer).
- ✓ 1. Two techniques are used: in maternal spindle transfer the mother's nuclear genetic material is moved into a donor egg before fertilisation, and in pronuclear transfer the fertilised embryo's nuclear material is moved into a donor embryo after fertilisation. Either way the child gets healthy donor mitochondria.
- ✓ 2. Only egg cells contribute mitochondria to the embryo, so only females pass on mitochondrial DNA variants; a father's sperm does not pass them on.
Remember · Mitochondrial DNA is inherited only from the mother. Mitochondrial replacement therapy: spindle transfer (before fertilisation) or pronuclear transfer (after fertilisation).
Sources
- HFEA (UK regulator): Mitochondrial donation treatment (maternal spindle transfer) ↗ “In MST, your nuclear genetic material is removed from your eggs and transferred into donated eggs which have had their nuclear genetic material removed. The eggs are then fertilised with sperm to create embryos. … In PNT, your eggs are fertilised with sperm in a lab to create embryos. The nuclear genetic material within each embryo is then transferred into embryos created using donated eggs and sperm from the sperm provider.”
- MedlinePlus (US National Library of Medicine): Inheritance patterns ↗ “Because only egg cells contribute mitochondria to the developing embryo, only females can pass on mitochondrial variants to their children.”
Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·