ROOM FOR ONE MORE

Replacing a mother’s diseased mitochondrial DNA allows a baby to carry genes from three people

MITOCHONDRIAL DNA

Mitochondrial DNA is inherited through a mother’s egg. If this DNA is diseased, a donor’s egg with healthy DNA can be used.

CLEARING THE WAY

The fertilised pronuclei containing the father’s and donor’s DNA is removed from the donor’s egg.

DISEASE RISK

If diseased mitochondria are transferred with the pronuclei, the embryo will have a combination of both donor and mother mitochondrial DNA.

NUCLEAR DNA

The father’s sperm is used to fertilise both the mother’s and donor’s egg cells, forming pronuclei that carry most of the genetic information in the cell.

A NEW HOME

The fertilised pronuclei from the mother’s egg are transferred into the donor egg, which has healthy mitochondria.