human conditions, medicine, technology

Three-Parent In Vitro Fertilization

Infertility is an extremely prominent issue for many couples. In fact, one in ten people in the U.S. will face fertility problems. A solution that increasing numbers of people turn to if they want to have a biological child is in vitro fertilization (IVF). About one million people in the U.S. seek fertility treatment of some kind every year, and some 300,000 resort to IVF. For many, it works. Each year, more than 1 percent of the babies born in the U.S. are through IVF. It’s a way for a couple to have a biological child when they might be unable to otherwise. In essence, in IVF sperm and eggs are removed from donors and fertilized outside of the body (in a Petri dish) and then implanted back into a woman’s uterus. IVF can also be used to prevent undesirable genetic mutations from being passed on to a child, and, with this in mind, a technique was recently developed that may make three-parent IVF possible.

egg sperm
A sperm and egg uniting.

What’s the advantage of having three donors compared to the usual two donors (sperm and egg) that are used in IVF therapies? It actually has to do with the mitochondria. While most of the genetic material, or DNA, in our cells is inside of our cell’s nucleus, some of our DNA is also in the mitochondria (a small structure that is inside all of our cells). There are actually many different types of diseases related to genetic abnormalities in the mitochondria’s DNA. Because a woman’s eggs have her own mitochondria, if she has a mitochondria-related genetic disease, she may decide not to have a biological child to avoid passing the disease on to her child. However, with the three-parent IVF, such a woman may be able to have her own biological child that wouldn’t inherit the disease by using another woman’s eggs (and mitochondria) and her own nuclear DNA. (Donor sperm makes up the third parent.)

How exactly three-parent IVF is done is as follows – a woman with healthy mitochondria donates eggs, which have their nucleus removed and replaced by the nucleus from cells of the mother-to-be. The egg is then fertilized by the father’s sperm. The resulting embryo can be implanted back into the mother’s uterus. This technique has been successfully used to make rhesus monkeys that are more than four years old, and it’s currently being reviewed by the FDA for approval in people in the U.S..

So while IVF is helping more couples to have their own biological child, it is also, controversially, clearly on the way to helping more couples have children that are healthier. The ethics and legalities of doing this and making “designer babies” will definitely be a hotly debated area for some time.

For much more information on the history, implications, and potential consequences of IVF, see Teisha J. Rowland’s book Biology Bytes: Digestible Essays on Stem Cells and Modern Medicine.

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