The possibility of using genetic material from three people for a single in vitro fertilization (IVF) attempt is getting mixed reviews in the scientific community in the United Kingdom, United States and in the general population. Supporters of the concept say 3-person IVF is good medicine, offering a way to eliminate certain inheritable diseases that leave a child sick, crippled and often at risk of early death. Critics contend it's a step toward creating a designer baby engineered for gender, looks, or intellect.
Traditional IVF involves a sperm and an egg that are united in the laboratory and implanted in the woman's womb, where it is expected to grow into a full-term, healthy pregnancy. Three-person IVF does that, too, but a third donor, a female, is needed to replace the mitochondrial DNA of the mother's if there is a known history of genetic illness involved.
Many diseases are passed down through families in the maternal line, from mother to child. These diseases are the result of genes in the female family members' mitochondrial DNA. All children inherit the mother's mitochondrial DNA, not the father's.
Three-person IVF unites the egg and sperm the same way it's done traditionally but the mitochondrial DNA from the egg is replaced with mitochondrial DNA from a female donor who has no history of genetic illness in her bloodline. By removing the flawed mitochondrial DNA, the chance of passing genetic disease to the child is eliminated entirely.
A similar procedure - cytoplasm transfer - was banned in the US in 2001 pending further study. The US Food and Drug Administration (FDA), which governs the approval process, cannot say whether or not any clinical investigations have been initiated or conducted at this time.
In cytoplasm transfer, no genetic material is removed; genetically damaged mitochondrial DNA would remain. The transfer involves cytoplasm from an older egg which is transferred into a new one. Cytoplasm is all the material inside a cell except its nucleus; mitochondria are part of the cytoplasm.
