Three-person in vitro fertilization (IVF) technique

Scientists in the UK have reported significant success with a three-person in vitro fertilization (IVF) technique that has spared children from inherited genetic diseases. This groundbreaking method aims to prevent the transfer of mutated mitochondrial genes from mothers to their offspring.

Purpose of the Technique

• The primary goal is to prevent the inheritance of severe genetic diseases that originate from mutations in the mother’s mitochondria.
• Mitochondria are the “powerhouses” of cells, and defects in their DNA can lead to incurable and potentially fatal disorders affecting vital organs like the brain, liver, heart, muscles, and kidneys.

How the Technique Works

The process, specifically “pronuclear transfer,” involves several precise steps:

• Fertilization: The mother’s egg is first fertilized with the father’s sperm.
• Nucleus Transfer (from affected parents): The “pronuclei” (containing the parental DNA from the fertilized egg) are removed from the mother’s fertilized egg.
• Nucleus Transfer (to donor egg): These pronuclei are then transferred into a donated fertilized egg from which its own pronuclei have been removed.
• Development: The resulting embryo develops with the nuclear DNA from the mother and father, but with healthy mitochondrial DNA from the donor, effectively replacing the faulty mitochondrial DNA.

Success of the Technique

• Scientists from Newcastle University reported that eight children in the UK have been successfully born using this technique, free from the inherited genetic diseases.
• The children range in age: one is 2 years old, two are between 1 and 2, and five are infants; all were healthy at birth.
• Blood tests confirmed very low or undetectable levels of mitochondrial gene mutations.
• All children have shown normal developmental progress.
• In six newborns, blood levels of mtDNA mutations were 95% to 100% lower, and in two others, they were 77% to 88% lower compared to their mothers.
• The procedure was tested in 22 women, resulting in eight births and one ongoing pregnancy, with no miscarriages in the seven uneventful pregnancies.

Ethical and Legal Considerations

• The development and implementation of this technique required decades of work, addressing complex scientific, technical, and ethical challenges, alongside extensive public and patient engagement.
• The UK became the first country globally to legalize research into mitochondrial donation treatment in humans in 2015.
• In contrast, the United States effectively banned pronuclear transfer for human use in the same year through a congressional appropriations bill, prohibiting the FDA from using funds for “heritable genetic modification.”