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?
Explanation
Statement 1 is correct: Mitochondrial Replacement Therapy (MRT) replaces mutated maternal mitochondrial DNA (mtDNA) with healthy donor mtDNA through two primary in-vitro methods:
– Maternal Spindle Transfer (MST): Administered before fertilization, where the nuclear spindle from the unfertilized mother’s egg is transferred into an enucleated donor egg.
– Pronuclear Transfer (PNT): Administered after fertilization, where pronuclei from the mother’s fertilized zygote are extracted and inserted into an enucleated, fertilized donor zygote.
Statement 2 is correct: Mitochondria exhibit strictly maternal inheritance. During fertilization, the sperm contributes its nuclear genome, while its tail and paternal mitochondria are degraded upon entry into the oocyte. Thus, cellular mtDNA is inherited solely from the mother, meaning an affected father cannot transmit mitochondrial diseases to his offspring.
Therefore, both statements 1 and 2 are correct — Option C.