All eight babies show no signs of having mitochondrial DNA disease. The babies, four girls and four boys, including one set of identical twins, were born to seven women at high risk of transmitting serious disease caused by mutations in mitochondrial DNA. The findings, reported today by the Newcastle team who pioneered mitochondrial donation using fertilised human eggs, indicate that the new treatment, known as pronuclear transfer, is effective in reducing the risk of otherwise incurable mitochondrial DNA diseases. 

Published in two papers in The New England Journal of Medicine (NEJM), the findings describe the reproductive and clinical outcomes of pronuclear transfer treatments performed to date. All babies were healthy at birth, meeting their developmental milestones, and the mother's disease-causing mitochondrial DNA mutations were either undetectable or present at levels that are very unlikely to cause disease.