Scientists in Britain have created human embryos with DNA from two women and one man. Patrick Chinnery, a professor of neurogenetics, said that the intent is not to alter genes but to exchange bad ones for good ones. They are trying to create healthy embryos in order to avoid passing on diseases such as muscular dystrophy, epilepsy, strokes and mental retardation.
The genes being replaced are the mitochondria, which is contained outside the nucleus of the egg. This is where problems in the genetic code generally are. Only small amounts of a person’s genes are in the mitochondria and most of the genes that make a person who they are reside inside the nucleus.
So far, 10 such embryos have been created, though they have not been allowed to develop for more than five days. Chinnery hoped that after further experiments in the next few years the process might be available to parents undergoing in-vitro fertilization.
More testing is necessary to assess the safety of the process before it is available as a potential treatment option.