In a heroic effort to prevent the transmission of disease from mother to child, researchers from the United Kingdom reported last week on the birth of eight babies—each of whom was conceived from one sperm and two eggs.
Although the babies, thus far, appear mostly healthy, some are wondering if science has taken a step too far. Will tinkering with nature like this have lasting consequences? And is the product of three distinct parents even human?
Development of the procedure, known as mitochondrial donation, has proceeded cautiously over decades. The aim has not been to create hybrid creatures but to prevent horrific disease linked to mitochondria, the microscopic power generators in the mother’s egg.
Mitochondrial disease is, in fact, devastating, affecting about 1 in 7,000 live births. Children can experience developmental delay, profound muscle weakness, hearing loss, blindness, strokes, and heart failure. Different types have been identified, and those with the worst symptoms die earliest, often before the age of 3. By contrast, children with mild or late-appearing symptoms can live full lives with few health setbacks.
To avoid mitochondrial disease, then, the aim is to transfer the combination of mom and dad’s DNA from a fertilized egg with sick mitochondria into an egg with healthy mitochondria stripped of its own DNA. It sounds so simple.
