Friday, September 09, 2005

UK will allow research on three-way embryos

The UK's Human Fertilisation and Embryology Authority (HFEA) has already approved research that would involve human cloning for non-reproductive purposes. Recently, according to The Register, an application that builds on that one was accepted, in which researchers will attempt to create an embryo that contains DNA from not one, not two, but three different people.

Turns out some diseases, such as muscular dystrophy, are triggered by defective genes in the maternal mitochondrial (extra-nuclear) DNA. By transplanting the healthy nucleus into a new, healthy egg, researchers hope they can eliminate these diseases--while still maintaining the "real parenthood" of good old Mom and Dad.

Missing in the dicsussion is the question, where in the world will all these eggs come from?

Read more here.

5 comments:

Kevin T. Keith said...

Since the technique is only relevant to women (not men) with heritable genetic diseases arising in mDNA, which are rare, it's likely that the demand for eggs for such procedures - if they became available - could be satisfied by the same commercial-egg-donor mechanisms that currently suffice for IVF.

As for the "3-person-DNA" bit, technically that's true, but one of those persons' DNA (the egg donor's) is only in the mitochondria, which are vital for cell functioning but do not contribute to obvious heritable characteristics like eye color, etc. The resulting child's "genes", as we commonly use that term, would all come from the mother and father who contribute the original sperm and egg and - presumably - serve as the child's parents.

In the case of male children, even that limited "3rd party" DNA will be lost in the next generation, because males do not pass on their mitochondria. Female children will pass on both their mother's nuclear DNA and their egg donor's mDNA, but, again, this makes little difference. Thus, all children in the female line will appear, by their mitochondria, to be descendants of the egg donor, and by their nuclear genes to be descendants of their "real" mothers (possibly causing some confusion in DNA genealogy studies), but it's the nuclear genes that contribute almost exclusively to making us what we are. Families of these children - male or female - will still be saying "She's got her grandmother's eyes" and "He's got his mother's smile" - and they'll be right.

The technology is interesting and, I suppose, revolutionary in some sense, but it's not a new version of genetic reproduction. We will all still have one genetic mother and one genetic father, even if some of us also have a mitochondria donor somewhere in our past.

Sue Trinidad said...

Yes, thanks for the clarification re parenthood on this scenario--didn't mean to imply that the mDNA swap would make an additional parent.

Your comment about the rarity of the conditions for which this technique might be helpful raises another couple of questions: how much effort and money should we spend to develop technological solutions to very rare diseases, in light of other healthcare spending priorities? And how much public funding should be spent to research treatments whose eventual use would be limited to those with the ability to pay for them? (Given that insurance generally doesn't cover IVF procedures, etc.)

Re the egg donation issue, I'm concerned about the presumption that there's an unlimited supply of human ova, and that the getting of same is wholly unproblematic.

Thanks for stopping by!

Kevin T. Keith said...

Re the egg donation issue, I'm concerned about the presumption that there's an unlimited supply of human ova, and that the getting of same is wholly unproblematic.

Well, I certainly don't make those presumptions, though it appears the egg-harvesting industry does. It is far from unproblematic; there are well-documented abuses in the field, and lingering questions about the propriety of paying large fees to donors. My point, though, was that the number of eggs needed for the "three-way DNA" procedure is likely to remain small compared to those needed for regular IVF, and whatever qualms we have about egg donation do not attach uniquely to the new procedure, so I don't think it is likely to greatly increase the degree of problems we now see.

[H]ow much effort and money should we spend to develop technological solutions to very rare diseases, in light of other healthcare spending priorities? And how much public funding should be spent to research treatments whose eventual use would be limited to those with the ability to pay for them?

These are perennial, but important, questions.

In practice, we finesse them by assuming that "basic research" is justified in at least two ways: (a) we cannot predict what the practical benefits of such research are, so we authorize a wide range of research in the expectation that good things will follow, and (b) basic research is so far removed from clinical practice that the money spent on it is not really attributable to this or that practical application - we're not really spending it on "Disease X" or "Disease Y", but on general medical knowledge, in the expectation that when a particular practical application appears on the horizon, private money will take over development. Clearly, in some cases, these assumptions are not justified; the "new genetics" procedures, like stem cell transplantations and the mDNA-donor procedure, are good examples of situations where the basic research is a potential clinical application. But these are exceptions; overall, we don't try to credit basic research dollars

Kevin T. Keith said...

Re the egg donation issue, I'm concerned about the presumption that there's an unlimited supply of human ova, and that the getting of same is wholly unproblematic.

Well, I certainly don't make those presumptions, though it appears the egg-harvesting industry does. It is far from unproblematic; there are well-documented abuses in the field, and lingering questions about the propriety of paying large fees to donors. My point, though, was that the number of eggs needed for the "three-way DNA" procedure is likely to remain small compared to those needed for regular IVF, and whatever qualms we have about egg donation do not attach uniquely to the new procedure, so I don't think it is likely to greatly increase the degree of problems we now see.

[H]ow much effort and money should we spend to develop technological solutions to very rare diseases, in light of other healthcare spending priorities? And how much public funding should be spent to research treatments whose eventual use would be limited to those with the ability to pay for them?

These are perennial, but important, questions.

In practice, we finesse them by assuming that "basic research" is justified in at least two ways: (a) we cannot predict what the practical benefits of such research are, so we authorize a wide range of research in the expectation that good things will follow, and (b) basic research is so far removed from clinical practice that the money spent on it is not really attributable to this or that practical application - we're not really spending it on "Disease X" or "Disease Y", but on general medical knowledge, in the expectation that when a particular practical application appears on the horizon, private money will take over development. Clearly, in some cases, these assumptions are not justified; the "new genetics" procedures, like stem cell transplantations and the mDNA-donor procedure, are good examples of situations where the basic research is a potential clinical application. But these are exceptions; overall, we don't try to credit basic research dollars to particular applications. (In part, we can't - what if the mDNA-donation procedure turns out to be useful to cure some other, less-rare disease that we can't anticipate now? How much of its development money was then "spent on" forseeable applications, and how much on the unforseeable one that developed later? Do we "de-credit" the research money from the original use, if another use turns up later?)

Another argument for not trying to account for basic research money too strictly is that we don't do such accounting in other areas. We fund lots of basic science with no clear hope of a practical application - again, in part because such applications often arise fortuitously, and in part because we have chosen to value knowledge-seeking to some degree for its own sake. But it is most often in the controversial cases that we demand a high bang-for-the-buck, arguing that this or that medical application is a waste of money while we blithely fund other research (observational astronomy?, SETI?, the Smithsonian Institution Folk Music archive?) that certainly offers no comparable benefit, or possibly no practical application of any kind. Though we would all like to see more efficient use of resources at all levels, we have no mechanism for ensuring "applicational efficiency" of basic research dollars - and it seems to me the demand for such efficiency in controversial cases is often a stalking horse for attacks on the research motivated by ideology. (I am not refering to posters on this blog.)

This is not an argument for paying no attention to how our money is spent, or for not setting spending priorities. But I do think there are practical and values-based reasons why demanding too-close an alignment between research funding and down-the-road clinical priorities is an elusive goal.

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