Swapping chromosomes among eggs could keep
embryos from inheriting genetic diseases.

What’s the News: Babies with three parents and fewer genetic diseases might soon be possible: A UK national health panel has found that techniques for swapping chromosomes between eggs so offspring don’t inherit disease-causing mutations from their mother’s mitochondria are not dangerous. The techniques, which have been tested in mice, monkeys, and human cells, still need to be studied more before making the transfer to the clinic, though, and as with all genetic engineering techniques, there’s a complex ethical maze ahead of researchers. 

What’s the Context:

In addition to the DNA you inherit from your mother and father’s egg and sperm, you also inherit a small amount of DNA that’s contained in the mitochondria of the egg. Mitochondria are cellular structures that produce energy for the cell, thought to be descended from bacteria that moved into cells millions of years ago, and have their own mini-genome. The mitochondria in sperm are destroyed during reproduction, so the only ones you inherit are your mother’s.
One child in 6,500 develops a disease linked to mutations in mitochondria, including type 2 diabetes, deafness, blindness, ...