The Truth about Mitochondrial Replacement

The United Kingdom’s House of Commons recently voted to amend the Human Fertilisation and Embryology Act 2008 to permit heritable genetic modification using a technology called mitochondrial replacement. This technology involves the creation of an embryo using the genetic material from three individuals: a man who contributes nuclear DNA; a woman who contributes nuclear DNA; and a woman who contributes mitochondrial DNA.

Usually, embryos are created using the sperm of one man and the egg of one woman. The sperm contains nuclear DNA and the egg contains both nuclear and mitochondrial DNA. Some women, however, have diseased mitochondrial DNA. If these women reproduce, they could pass their mitochondrial disease along to their children. This could mean serious health problems for these children including neurodegenerative disease, stroke-like episodes, blindness, and muscular dystrophy. To avoid the birth of children with these types of mitochondrial diseases, scientists want to replace the woman’s unhealthy mitochondrial DNA with healthy mitochondrial DNA from an egg donor, and then create a healthy embryo using IVF. The donated mitochondrial DNA would be passed on to the...