UPSC CSE Prelims
Question 72
In the context of hereditary diseases, consider the following statements:
- 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?
View correct answer and explanation
Correct answer: C
Correct Option: C (Both 1 and 2)
Explanation: Mitochondrial replacement therapy can transfer nuclear material before or after in-vitro fertilisation to avoid a mother’s defective mitochondria. Mitochondrial DNA is ordinarily inherited maternally.
Statement / Pair / Item-wise Analysis:
1. Correct / qualifies - Maternal-spindle transfer is performed before fertilisation; pronuclear transfer can be done after it.
2. Correct / qualifies - Mitochondrial DNA and the associated inherited mitochondrial disease are usually passed through the mother.
Option-wise Analysis:
A. Incorrect-omits valid item 2 (Mitochondrial DNA and the associated inherited mitochondrial disease are usually passed through the mother).
B. Incorrect-omits valid item 1 (Maternal-spindle transfer is performed before fertilisation; pronuclear transfer can be done after it).
C. Correct-selects exactly the supported statements/items: 1, 2.
D. Incorrect-omits valid item 1 (Maternal-spindle transfer is performed before fertilisation; pronuclear transfer can be done after it); omits valid item 2 (Mitochondrial DNA and the associated inherited mitochondrial disease are usually passed through the mother).
Review note: Rare reports of paternal mitochondrial transmission do not change the standard inheritance pattern tested.