Genetically Engineering Babies With Less Disease—and 3 Parents—Seems Safe

By Veronique Greenwood | April 21, 2011 9:22 am

Swapping chromosomes among eggs could keep
embryos from inheriting genetic diseases.

What’s the News: Babies with three parents and fewer genetic diseases might soon be possible: A UK national health panel has found that techniques for swapping chromosomes between eggs so offspring don’t inherit disease-causing mutations from their mother’s mitochondria are not dangerous. The techniques, which have been tested in mice, monkeys, and human cells, still need to be studied more before making the transfer to the clinic, though, and as with all genetic engineering techniques, there’s a complex ethical maze ahead of researchers. 

What’s the Context:

  • In addition to the DNA you inherit from your mother and father’s egg and sperm, you also inherit a small amount of DNA that’s contained in the mitochondria of the egg. Mitochondria are cellular structures that produce energy for the cell, thought to be descended from bacteria that moved into cells millions of years ago, and have their own mini-genome. The mitochondria in sperm are destroyed during reproduction, so the only ones you inherit are your mother’s.
  • One child in 6,500 develops a disease linked to mutations in mitochondria, including type 2 diabetes, deafness, blindness, and neurological problems; as many as 1 in 250 people carry mutations that might cause disease when passed on.
  • Transferring chromosomes (genetic structures found in the nucleus) from one cell to another is old hat in biology, so it makes sense that researchers would try the same trick to avoid diseases that come from DNA mutations in mitochondria (which are outside the nucleus). If chromosomes removed from an egg carrying mitochondrial mutations are inserted in a healthy egg whose own chromosomes have been discarded, the mitochondria are left behind, and the offspring don’t have the disease. The offspring instead inherits the mitochondrial DNA of the donor egg—hence the “three parent” idea.

How the Heck:

  • The panel’s report, submitted to the UK’s Human Fertilisation and Embryology Authority, reviewed two techniques.
  • In the first technique, the chromosomes of an unfertilized egg are inserted into a donor egg whose nucleus has been removed; the egg is fertilized using in vitro fertilization (IVF) and implanted into the mother. Rhesus macaques born this way are healthy and develop normally, scientists reported in Nature in 2009; the team is now testing it in human cells (via The Great Beyond).
  • The other technique transfers the nucleus of a fertilized egg to a fertilized donor egg whose nucleus has been removed. It’s been tested in fertilized human eggs that could not be used for IVF and the eggs developed normally to the 100-cell stage. But there’s an ethical quandary here: it involves the destruction of the donor egg after it’s been fertilized. (More details on the ethics of these techniques in general in Wired Science’s coverage of that 2010 study.)

The Future Holds: For starters, the technique tested in macaques should be tested in human cells and the technique tested in human cells should be tested in monkeys, says the panel. If the techiques continue to prove safe, it’s likely they’ll begin to be considered for clinical use. It’s difficult to say how that will proceed–the issue of destroying potentially viable fertilized eggs may be deemed unacceptable in some countries. There’s the issue, too, that the mitochondria of the third “parent” will be passed on to the child, the child’s children, children’s children, and so on, meaning this genetic engineering is heritable. How will nations (and individuals) react to having a third person’s genes permanently added to their own?

Image credit: Wikimedia Commons, 8-cell embryo.

CATEGORIZED UNDER: Health & Medicine
  • Prof.Pedant

    I don’t see any ethical difficulties, the parents have a healthy child and the child has an aunt or cousin who is a bit closer to him or her biologically than usual. Raising the healthy child to be a happy healthy adult will provide the parents and other relatives with more ethical quandaries than how the child came into existence ever would.

  • http://DiscoverMagazine Templar 7

    Awesome!! Now we can create a race of superhumans like Hitler wanted to!!! Not to mention the power to alter life as easy as throwing a fetus in a abortion bucket…and who thinks that the peoples of this world want more mouths to feed, no way! Talk about budget cuts (Republicans), heres a newsflash for you: It’s cheaper to get rid of a mouth to feed then to fund a happy lil clinic of death.

    The beauty of it is it’s not my problem:)

  • Kris

    Gattaca, here we come!

  • Steve

    I am the only person that thought gattaca didn’t handle its message correctly. You have genetically engineered people that are by design better, the future was looking like everything was going pretty good and the main character proved that he was just as super but what the movie never showed is any other normal people being super, so I kind of never really cared about them… (yes i do know the whole discrimination and such but it is pretty much implied by the tone that non modded humans where on the decline)

  • Oli

    The ‘third parent’ thing might be nice for lesbian and gay couples. If they use a surrogate parent, they can still both be biological parents of the child.

  • Vaughn

    you just don’t get it do you

  • Ashley

    I’d love for someone to explain to the rest of us how taking an egg that hasn’t even been fertilized and using its healthy mitochondria to help a couple conceive a healthy child is even remotely related to abortion? And really, Templar 7….. “It’s cheaper to get rid of a mouth to feed than to fund a happy lil clinic of death”? What do you think abortion IS?
    Having said that….I think the whole idea is pretty amazing. I’d never spend the money on it as a consumer, even if I had messed up mitochondria. Hell, adopt!! ^_^

  • Iain

    Ashley did you miss “transfers the nucleus of a fertilized egg to a fertilized donor egg whose nucleus has been removed”? See, that’s the abortion part. Two fertilized eggs make one.

    Bur we really don’t need more or better reproduction right now. We need to cap our population! But of course the problem as always is, Who will decide what.

  • Oblivious

    I will never understand why so many people try to lay claim to the use of my (or anyone else’s for the matter) eggs and body. By that logic all women are naturally and unavoidably genocidal maniacs because we can’t possibly conceive each and every of the millions of eggs we carry.

    If we can use a handful of those wasted eggs to further medical science and better our everyday lives for the advancement of our species, isn’t THAT worth it?

    Why don’t we create solutions instead of propagating problems? We can terraform desserts into cropland. Why not cry about the unfairness of refusing to use that technology because of dollars of all things?

  • http://N/A Gloria

    I wonder if this process is being developed so that gay persons can have children using DNA from both partners. If so, it is a very selfish act.

  • Allison

    It is a necessary fact that everyone among us must be allowed to voice his or her opinion, regardless of how offensive it is to our personal beliefs. If we commanded everyone who offends us to remain silent and spare us their idiocy, we’d have a world full of stuffy people who never challenge or examine themselves. The last thing we need is to descend further into the pit of absolutist ideology, presented to us as a dichotomy wherein all the vibrant colors have been muted to suit a less curious intellectual palette.

    Having said that, I think that the dripping sarcasm and outright hyperbole of a few betrays a greater lack of understanding as well as misinformation on the part of politicized interests. It is easy to allow our passions to get the better of us on a subject which is not widely understood and the debate around which is colored by passionate discourse on many sides.

    I believe it is worth the time to examine the implications of the uses of genetic engineering. In doing so we can present rational cases for it’s use in the context of an ethical framework and show others through our words that it’s not the bugbear that they think it is. After all, we are talking about decreasing the incidence of tragic and often life threatening medical conditions, not creating supermen.

    Just a few things to consider.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day's most compelling topics.

See More

Collapse bottom bar