This cunning biotechnology scheme, known as mitochondrial replacement therapy (MRT), currently only legal in the UK, is absolutely out of bounds. Even though you’re not messing with the “majority” (nuclear) DNA, genes are genes, and this mitochondrial “minority” DNA needs to stay put.
These genes are, of course, designed to make cell energy possible. (A brief reminder from HS biology: mitochondria are the powerhouses of the cell, and supply energy to the cells using oxygen and nutrients, which is the very reason we eat and breathe.) And what good is a organism without energy anyway?
Indeed, when mitochondrial DNA is mutated, can lead to such ailments as blindness and seizures. But putting a foreign mitochondrion into a cell, whether it is truly genetically engineering or not, is still playing God, like much of biology is now.
Details can be found in the above article, and I have some supplemental info from my own keen understanding of Biology! Between the head of the sperm and its tail, there is a middle axis of mitochondria. However, the nucleus is contained strictly in the head of the sperm cell. (I read this in McGraw-Hill’s Encyclopedia of Science and Technology, an excellent work on STEM topics.) The female egg cell is a more typically structured cell, so it is more likely to pass its mitochondria to the next generation. But even if the offspring is disabled due to a faulty mitochondrial genome, it is God’s will.
Let’s eliminate eugenics!