Embryo gene editing: from theory to practice

The Guardian reported yesterday that the first UK baby with DNA from three people has been born in IVF treatment. In 2017, the Newcastle Fertility Centre became the first authorised UK centre to provide mitochondrial donation treatment ("MDT") to patients. The therapy is designed to avoid the inheritance of mitochondrial defects which would result in devastating disease. MDT is provided subject to approval by the UK’s Human Fertilisation and Embryology Authority ("HFEA"), which is given on a case-by-case basis.

MDT involves a patient's egg being fertilised with her partner's sperm, and the sperm also being used to fertilise a donor egg. The nucleus from the patient's embryo is removed and inserted into the donor's embryo (the nucleus from which is removed and destroyed). As such, the patient's nucleus benefits from the healthy mitochondria from the donor's embryo and avoids the unhealthy mitochondria within the patient's embryo. This particular type of MDT is called pronuclear transfer. This gene therapy reduces the chances of the resulting child suffering from the genetic disorder contained in the patient's mitochondria. The chances cannot be said to be eliminated because a very small amount of the patient's mitochondria is transferred with the patient's nucleus. This can multiply during embryonic development.

The Newcastle clinic has not released birth information with a view to preserving patient confidentiality. However, the Guardian submitted a Freedom of Information Act request, to which the HFEA responded. The agency responded that "less than 5" babies in the UK having been born following MDT, as at April 2023, thus confirming that this cutting edge technology has been put to practice. Again, the exact number has not been disclosed to protect patient confidentiality. It will be interesting to see what if any safety information is gathered from long term monitoring of this case/these cases. We understand that agreeing to this follow-up monitoring is not compulsory.