The controversial trial of mitochondrial donation treatment has proven a success in the UK, preventing a newborn baby from inheriting defective genes.
ADVERTISEMENTAn IVF baby created from the DNA of three separate people has been born in the UK, as scientists try to tackle the passing on of defective genes carried in the mother’s mitochondria.
The baby was born to one genetic father and two genetic mothers after researchers at the Newcastle Fertility Centre were granted permission to trial the controversial procedure back in 2017.
The first baby to be born from mitochondrial donation treatment (MDT) was in Mexico in 2016 as the mother had genes for Leigh syndrome, a rare neurometabolic disorder that affects the central nervous system and is often fatal.
She had previously experienced four miscarriages and had two children, one of whom died aged six and the other at eight months.
How does mitochondrial donor treatment work?
Mitochondrial DNA is passed on by the mother and accounts for 0.1 per cent of a child’s inherited genetics. If doctors detect abnormalities in the biological mother’s mitochondria, MDT is one possible solution.
MDT takes the nuclear DNA from the parents’ embryo (so the core genes like hair and eye colour will match the parents) and inserts the nucleus into the donor’s fertilised egg with healthy mitochondria.
The resulting baby has the vast majority of its DNA from the mother and father, around 99.8 per cent. But there’s a tiny amount of genetic material from the donor - estimated to be around 37 genes altogether.
What do mitochondria do - and how can they affect the health of babies?
Humans have 20,000 genes, which at the embryonic stage are predominantly concentrated in the nucleus. However, surrounding each nucleus in a fertilised egg are thousands of mitochondria which have their own genes.
In an optimally healthy embryo, the mitochondria’s main role is to provide energy to the cells that will eventually form our organs. So if these are damaged or have mutations, it’s the brain, heart, liver, and other vital organs that could be impacted as a baby grows.
Mitochondrial diseases affect one in 4,300 births worldwide.
"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," Dagan Wells, a professor of reproductive genetics at the University of Oxford, told The Guardian newspaper.
"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".
