A baby born with genes from three people has been born in the UK for the first time. But the process carries risks.
A baby with the genetic information of three people has been born in Great Britain for the first time. The child was conceived at the Newcastle Fertility Centre, a fertility clinic in Newcastle, northeast Britain, according to a report by the British Guardian.
The so-called mitochondrial donation was used for this – a procedure that was approved by parliament there in 2015. Tissue from the egg cells of healthy donors is combined with the sperm and egg cells of the biological parents. In this way, embryos can be created that are free of harmful mutations in the genes that the biological mother carries and would most likely pass on to the child.
“Three-parent baby” carries 37 genes from the donor
Specifically, during mitochondrial donation, the sperm and egg cells of the biological parents are merged with the mitochondria from the egg cell of the donor. The resulting embryo carries the mother’s and father’s DNA, as usual, plus a small amount of genetic material – about 37 genes – from the donor.
This process has led to the term “three-parent baby”. In fact, more than 99.8 percent of a child’s DNA comes from the mother and father.
The mitochondria
Mitochondria are also referred to as the “power plants of the cell”. They supply vital energy to the cells that make up our organs. Mitochondria have 37 genes of their own that are responsible for the formation of 13 different proteins. This genetic information is only passed on to the offspring in the maternal mitochondria. All of a woman’s children have the same mitochondrial DNA. Mutations that damage mitochondria tend to affect tissues that require a lot of energy: the brain, heart, muscles, and liver.
Humans inherit all of their mitochondria from their mothers, so harmful mutations in these so-called “cell batteries” can affect all of a woman’s children.
Natural conception is risky in such cases. Some children are born healthy because they inherit only a tiny portion of the mutated mitochondria. But others inherit much more and can develop serious, progressive, and often fatal diseases. About one in 6,000 babies is affected by mitochondrial disorders.
Research on this procedure was spearheaded by doctors at the Newcastle Fertility Centre. The clinic is also the only one in the UK to date to be licensed for this procedure.
Donation carries risks
Mitochondrial donation – also known as mitochondrial replacement therapy – is granted in the UK by the UK Human Fertilization and Embryology Authority (HFEA) on a case-by-case basis.
The donation can be made in two different ways. With the method used in Newcastle, eggs from the affected mother and a healthy donor are first fertilized with the father’s sperm. The core genetic material is then removed from the donor’s egg and replaced with that of the couple’s fertilized egg. The resulting egg cell contains the complete set of chromosomes from both parents, but the healthy mitochondria of the donor. This egg is then placed in the uterus.
However, this procedure is not without risk. Recent research has shown that in some cases, the very few abnormal mitochondria that are inevitably transferred from the mother’s egg to the donor egg can multiply in the baby in the womb. This can lead to the child becoming ill.
The UK is not the first country to have babies born with MDT. In 2016, a US doctor announced the world’s first birth with MDT after treating a woman with mitochondrial mutations that cause a deadly disease called Leigh syndrome.
