1. Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of the egg.
2. A child inherits mitochondrial diseases entirely from mother and not from father.
Which of the statements given above is/are correct?
Explanation
Mitochondrial diseases are a group of genetic disorders caused by dysfunction in the mitochondria, the cell’s energy-producing structures.
Statement 1 is correct: Mitochondrial Replacement Therapy (MRT) is an advanced reproductive technique designed to prevent the transmission of mitochondrial diseases from mother to child. MRT involves replacing defective mitochondria in an egg or embryo with healthy mitochondria from a donor. This can be achieved through methods such as:
Spindle Transfer: Performed before fertilization, where the nuclear DNA from the mother’s egg is transferred to a donor egg with healthy mitochondria, followed by fertilization. Pronuclear Transfer: Conducted after fertilization, where the pronuclei (genetic material) from a fertilized egg are transferred into a donor zygote that has healthy mitochondria. These techniques aim to ensure that the resulting child inherits healthy mitochondria, thereby preventing mitochondrial diseases.
Statement 2 is correct: A child inherits mitochondrial diseases entirely from the mother and not from the father. Mitochondria are unique organelles within cells that have their own DNA, known as mitochondrial DNA (mtDNA). Unlike nuclear DNA, which is inherited from both parents, mtDNA is typically inherited exclusively from the mother. This is because the mitochondria in the sperm are usually destroyed or degraded after fertilization, and thus do not contribute to the embryo’s mitochondrial pool. Consequently, if a mother has a mitochondrial disease (caused by mutations in her mtDNA), there is a risk that she can pass it on to her children, while fathers do not pass on mtDNA to their offspring, and thus do not transmit mitochondrial diseases.