First UK baby born with DNA from three people

The first UK baby created with DNA from three people has been born after doctors performed a groundbreaking IVF procedure that aims to prevent children inheriting incurable diseases.

- Ian Sample

The technique, known as mitochondrial donation treatment (MDT), uses tissue from the eggs of healthy female donors to create IVF embryos that are free from harmful mutations their mothers carry and are likely to pass on to their children.

Because the embryos combine sperm and egg from the biological parents with tiny battery-like structures called mitochondria from the donor's egg, the resulting baby has DNA from the mother and father as usual, plus a small amount of genetic material - about 37 genes - from the donor. The process has led to the phrase "three-parent babies", though more than 99.8% of the DNA in the babies is from the mother and father.

Research on MDT, which is also known as mitochondrial replacement therapy (MRT), was pioneered in the UK by doctors at the Newcastle Fertility Centre.

The work aimed to help women with mutated mitochondria to have babies without the risk of passing on genetic disorders. People inherit all their mitochondria from their mother, so harmful mutations in the "batteries" can affect all of the woman's children.

For affected women, natural conception is often a gamble. Some babies might be born healthy because they inherit only a tiny proportion of the mutated mitochondria. But others may inherit far more and develop severe, progressive and often fatal disease. About one in 6,000 babies are affected by mitochondrial disorders.