The United Kingdom's House of Commons has voted to allow creation of a human embryo using the DNA from three people. The intent of this technology is to prevent inherited mitochondrial diseases.
If the legislation is approved by the House of Lords, the United Kingdom will be the first country to allow this type of cell manipulation in humans. If it is approved, the first baby created with this technology could be born as soon as next year. Clinics that offer this type of modification will have to apply for a special license. Any children born using the technology will be closely monitored for health problems.
The genes will come from two women and one man. Mitochondrial diseases are caused by defective mitochondria that are passed down from the mother to the embryo. Mitochondria are the powerhouses of the cell and everyone inherits all their mitochondria from their mothers through the egg cell. Mitochondrial diseases cause brain damage, muscle wasting, heart failure, and blindness.
This technology can be done in two ways: In one, the nuclei of an embryo with defective mitochondria are removed and placed into a donor embryo with healthy mitochondria that has had its nuclei removed. In a second method, a nucleus from an egg cell with unhealthy mitochondria is removed and placed into a healthy donor egg cell that has had its nucleus removed. The egg is then fertilized. In either method, the modified embryo is then implanted into the mother's uterus.
Unlike genetic modification, where a gene from one species is transferred into another, this technology uses only human genes. The genetic changes will be passed on to the next generation. Each of these babies would have 99% of their DNA from a man and a woman-the parents who would presumably raise the child-and 1% from another woman who does not carry mitochondrial disease.
Opponents of the legislation fear that it will open the doors to children who have been modified for reasons other than to prevent or treat diseases. The Roman Catholic Church has long opposed any forms of artificial reproductive techniques, which would include this mitochondrial replacement technique.
