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upstart writes:

Mitochondrial donation treatment aims to prevent children from inheriting incurable diseases:

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 from inheriting incurable diseases.

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 comes 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 children a woman has.

[...] The Newcastle process has several steps. First, sperm from the father is used to fertilise eggs from the affected mother and a healthy female donor. The nuclear genetic material from the donor's egg is then removed and replaced with that from the couple's fertilised egg. The resulting egg has a full set of chromosomes from both parents, but carries the donor's healthy mitochondria instead of the mother's faulty ones. This is then implanted in the womb.

The procedure is not without risks. Recent research has found that in some cases, the tiny number of abnormal mitochondria that are inevitably carried over from the mother's egg to the donor egg can multiply when the baby is in the womb. So-called reversion or reversal could lead to a disease in the child. "The reason why reversal is seen in the cells of some children born following MRT procedures, but not in others, is not fully understood," said Dagan Wells, a professor of reproductive genetics at the University of Oxford who took part in the research.

[...] The UK is not the first country to create babies from MDT. In 2016, a US doctor announced the world's first MDT birth after treating a Jordanian woman who carried mitochondrial mutations that cause a fatal condition called Leigh syndrome. Prior to the treatment, performed in Mexico, the woman had four miscarriages and two children. One died aged six, the other lived for only eight months.

"So far, the clinical experience with MRT has been encouraging, but the number of reported cases is far too small to draw any definitive conclusions about the safety or efficacy," said Wells. "Long-term follow-up of the children born is essential. The stage of development when reversal happens is unclear, but it probably occurs at a very early stage. This means that prenatal testing, carried out [at] about 12 weeks of pregnancy, may well succeed in identifying if reversal has occurred."

Previously:
    FDA Warns Doctor Against Marketing Three-Person IVF Technique
    Baby Girl Born in Ukraine Using Three-Parent Pronuclear Transfer Technique
    Fatal Genetic Conditions Could Return in Some 'Three-Parent' Babies
    First Three-Person Baby Born Using Spindle Nuclear Transfer
    Newcastle University Study Verifies Safety of Three-Person IVF

Original Submission