Overview

• Pronuclear transfer merges parental nuclear DNA with donor mitochondria under strict UK authorization to block transmission of maternal mitochondrial mutations.
• Two New England Journal of Medicine studies report that all eight infants have developed normally through 18 months with no clinical signs of mitochondrial disease.
• Genetic analyses detected mutant maternal mtDNA levels well below thresholds linked to symptoms and researchers plan further protocol refinements to minimize carryover.
• The Human Fertilisation and Embryology Authority oversees each case and will track participants for several years to confirm procedure safety.
• Germany’s Embryonenschutzgesetz prohibits egg donation and leaves the country unable to adopt mitochondrial replacement therapy while legal and ethical debates continue.