it can lead to children being born with severe muscle wasting conditions. it can affect the brain, the eyes, in fact, the entire body. and many times children miscarry. so this is designed to try and help couples have a healthy child. now, what it involves, the mitochondria, they have a tiny amount of dna, which is always passed down through the maternal line from the mother s egg. what happens is they use a donor egg to have the healthy mitochondria, but crucially, the extra dna, and it s about 0.1% of the entire dna that that child will have is outside the nucleus. so all the characteristics, the traits that you get from your parents will be the same. and this extra dna, this tiny amount of dna sits outside. and it s now been done at least once