Three-Parent Baby Technique Could Create Babies At Risk of Severe Disease

MIT Technology Review has revealed two cases in which babies conceived with the three-parent baby technique have shown what scientists call 'reversion.' 'In both cases, the proportion of mitochondrial genes from the child's mother has increased over time, from less than 1% in both embyros to around 50% in one baby and 72% in another,' they report. From the report: When the first baby born using a controversial procedure that meant he had three genetic parents was born back in 2016, it made headlines. The baby boy inherited most of his DNA from his mother and father, but he also had a tiny amount from a third person. The idea was to avoid having the baby inherit a fatal illness. His mother carried genes for a disease in her mitochondria. Swapping these with genes from a donor -- a third genetic parent -- could prevent the baby from developing it. The strategy seemed to work. Now clinics in other countries, including the UK, Greece, and Ukraine, are offering the same treatment. It was made legal in Australia last year. But it might not always be successful.

Fortunately, both babies were born to parents without genes for mitochondrial disease; they were using the technique to treat infertility. But the scientists behind the work believe that around one in five babies born using the three-parent technique could eventually inherit high levels of their mothers' mitochondrial genes. For babies born to people with disease-causing mutations, this could spell disaster -- leaving them with devastating and potentially fatal illness. The findings are making some clinics reconsider the use of the technology for mitochondrial diseases, at least until they understand why reversion is happening. 'These mitochondrial diseases have devastating consequences,' says Bjorn Heindryckx at Ghent University in Belgium, who has been exploring the treatment for years. 'We should not continue with this.' 'It's dangerous to offer this procedure [for mitochondrial diseases],' says Pavlo Mazur, an embryologist based in Kyiv, Ukraine, who has seen one of these cases firsthand.

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