The House of Lords voted by 280 votes to 48 on Tuesday evening to approve the technique which uses nuclear DNA from one woman and mitochondria (which contain a very small amount of DNA) from another woman, along with DNA from one man.

Mitochondrial DNA transfer, which was developed by British scientists, allows IVF clinics to replace an egg's defective mitochondria with healthy ones from a female donor, to prevent children suffering incurable genetic diseases such as muscular dystrophy and Leigh’s disease.

Dr Mark Downs FSB, chief executive of the Society of Biology said:
“This is a great day for UK science and for many families affected by incurable mitochondrial diseases. This landmark decision will ensure mothers who carry faulty mitochondria can have healthy children free from the devastating conditions caused by these particular defects. We fully support the introduction of regulations which will facilitate treatment while carefully monitoring outcomes.”

Clinics in UK will be able to apply for licenses from this autumn after MPs approved new rules earlier this month. The first baby conceived using mitochondrial donation could be born as early as 2016.

The mitochondria are often referred to as the ‘batteries’ of the cell, as they are responsible for generating cellular energy. Mitochondrial DNA (mtDNA) only contains 37 genes, all of which are thought to be associated only with the production of cellular energy. The nuclear DNA (nDNA) contribution of the two parents contains about 25,000 genes and accounts for the characteristics typically thought of as being familial.

Mutations in the maternally inherited mtDNA, can have serious health consequences if the mitochondria are not able to produce an adequate amount of energy to meet the demands of cells or tissues. Therefore, mitochondrial mutations can have a serious effect on organs that require a lot of energy, like the heart, brain, kidneys, and major muscle groups. There is no cure for diseases that result from mutated mitochondria, and often the symptoms cannot be treated.