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Question 571

Genetics → General

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Classification

Speciality
Obstetrics and Gynaecology
Group
Basic
Title
Genetics
Topic
General
Subtopic 1
Mitochondrial DNA
Subtopic 2
Maternal inheritance
Subtopic 3
Transmission through daughters and sons
Question Type
SBA

Question

SSBA
Question Header
Which statement best describes their potential to transmit this mitochondrial DNA mutation to their children?
Question Stem
A woman and her brother both carry a mitochondrial DNA mutation inherited from their mother. Each is considering having children. The mutation is confined to mitochondrial DNA.

Options

A Both siblings can transmit it because both carry the mutation
B Only the brother can transmit it because sperm contain mitochondria
C Neither sibling can transmit it because mitochondrial inheritance stops after one generation
D Only the woman can transmit it because mitochondrial inheritance is maternal
E The woman can transmit it to daughters, whereas the brother can transmit it to sons

Explanation

Mitochondrial DNA is inherited from the mother, not the father. Paternal mitochondria do not contribute to mitochondrial inheritance after fertilisation. Consequently, although both siblings inherited the mutation from their mother, only the daughter can transmit the mitochondrial trait to a subsequent generation.

Option Validity

A) Carrying a mitochondrial mutation does not confer paternal transmission. The brother cannot pass mitochondrial DNA to his children.

B) Sperm contain mitochondria, but these do not establish paternal mitochondrial inheritance after fertilisation.

C) Maternal transmission can continue through daughters; it is not limited to a single generation.

E) Mitochondrial inheritance depends on the transmitting parent being the mother, not on matching the sex of the parent and child. The brother cannot transmit it to sons.

Further Reading

Saxena R. Textbook for MRCOG-1: Basic Sciences in Obstetrics and Gynaecology. 1st ed. Jaypee Brothers Medical Publishers; 2016. Chapter 8: Genetics — Mitochondrial DNA. Printed pages 255–256.

Source & metrics

Authored Difficulty
5.00
Evaluation Score
—
Destination
Site
Source
Saxena - MRCOG-1 Basic Sciences - Genetics
Source Section
Chapter 8 — Genetics — Mitochondrial DNA
Source Locator
Printed pages 255–256
Updated
2026-10-06 01:57:35
Difficulty Factor
Not available yet
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