May 09, 2007
Embryo Eugenics Finds New Uses
When using in vitro fertilization (IVF) to start a pregnancy in a lab dish it is possible to genetically test each embryo to avoid undesirable genetic variations or to choose desired genetic variations. William Saletan reports the list of reasons people use pre-implantation genetic diagnosis (PGD) for embryo selection is growing.
In its early days, PGD targeted fatal childhood diseases such as Tay-Sachs. But a new survey of U.S. fertility clinics, scheduled for release this week by the Genetics and Public Policy Center, suggests the line is moving. Among clinics that offer PGD, 28 percent have used it to target genes whose associated diseases don't strike until adulthood. The list includes Alzheimer's, which afflicts some people in their 30s but usually arrives much later. According to next month's Journal of Clinical Oncology, PGD has also been used to wipe out colon cancers that don't develop until age 45 to 55 and are treatable, if detected early, with survival rates of 90 percent.
For some of these adult-onset genes, the risk of illness is less than 50 percent. But it feels mean, even arbitrary, to quibble about probabilities. American clinics target these genes anyway, to prevent "cancer predisposition syndromes," if not cancer itself. Even if your child never gets sick, just knowing he has the gene can cause anxiety, as British regulators noted four months ago when they approved PGD for colon cancer.
The use of PGD has now spread beyond just avoidance of severe diseases. Some prospective parents choose to avoid genetic variations that give fairly low probabilities of diseases such as colon cancer. I see this as a waste of time for some diseases. A baby born today will not face serious risk of colon cancer until the 2050s. Well, by the 2050s I expect cancer will be easily curable or avoidable.
The other reason to refrain from selecting against genetic variations that create low risk of some diseases is that these variations might provide benefits as well. Functionally significant genetic variations found in substantial portions of the human population probably got selected for. Many genetic variations that cause specific disease risks also probably deliver some as yet undiscovered benefit.
Scientists are going to discover the costs and benefits of hundreds of thousand and possibly millions of genetic variations. As the significance of hundreds of thousands of genetic variations becomes known the advantages of using IVF with PGD will grow enormously. I expect at some point in industrialized countries natural conception will become less used than IVF. This transition point probably will happen in the next 30 years because we'll know what most of the genetic variations mean within 30 years.
Once we know a lot about hundreds of thousands of genetic variations then genetic testing of a dozen or so embryos is going to be viewed as too confining and constricting. IVF and PGD only let you choose among those combinations of parental DNA that actually happen in the half dozen or dozen embryos which will result from basically random arrangement of DNA from two parents. People will start pining for the ability to select which of each pair of chromosomes to give to junior.
The development of biotechnologies that enable selection between chromosomes will enable even greater control over which genetic variations parents will give to their offspring. Beyond that capability the next step will be gene therapy to create offspring that have genetic variations in combinations that could not occur as a result of normal sexual reproduction. Once that becomes possible the rate of human genetic change will skyrocket.
In the United States I am not expecting many restrictions on the use of IVF and PGD to select for desired genetic features beyond disease avoidance. As each new capability hits the market potential parents will demand the freedom to choose genetic features for many reasons. Looks and intelligence will be two big motivators for use of PGD and, further into the future, use of chromosome selection and gene therapy.
The ability to select genetic variations for offspring will make reproduction more appealing. This capability will allow lowering of many risks (e.g. of retardation, autism, attention deficit, and tendencies toward anger and criminality) The ability to reduce risks will greatly increase the likelihood that offspring will meet parental hopes. So kids will be born who are better looking, smarter, and better behaved. I expect an increase in fertility due to the increased likelihood that prospective parents will get children who will have desired features.
Thanks to Ivan Kirigin for the heads-up.
There is endless merciless yammering from people at both ends of the political spectrum about reprogenetics and how bad and evil it is. They can rant and rave about this but legally there is very little they can do to stop these technologies. In 1948, SCOTUS ruled that reproduction was an unfettered right and that no law can be passed to restrict a person's right to reproduce. This ruling was in response to the common practices of coercively sterilizing people who were deemed "unfit" for reproduction (mentally ill, reduced cognitive capability, habitual criminals, etc.) by society.
Of course, there was no reprogenetics at the time, but it is not a stretch to believe that such a ruling would include whatever reproductive technologies that are safe and available to facilitate such reproduction. I believe that any attempt to criminalize reprogenetics technology is likely to be overturned by SCOTUS on the basis of this 1948 ruling. If people cannot be coercively prevented from having kids of sub-normal cognitive ability, how can it be argued that people can be coercively prevented from having kids of super-normal cognitive ability?
I think PGD and IVF will become big. I also expect ectogenesis (exowombs) to become very popular as well. However, I think that germline genetic engineering of kids will not be accepted by the marketplace for a long period of time. The reason is that the first technologies are largely preventative in nature. They reduce risk. Germline genetic engineering, on the other hand, is an additive technology in the sense that you are trying to create something new. This has increased risk. Prospective parents are, by nature, inherently risk adverse and, therefor, will not pursue germline genetic engineering until they are certain that the technology (and modifications) are safe and effective. For this reason, I think it will be 20-30 years before germline genetic engineering becomes widely accepted by prospective parents.
Personally I support full freedom to genetically tinker, without any limit. I don't think the "loss of beneficial genes" thing matters. After all, what we took out can be put back in (or better yet, debugged first).
Gene tinkering isn't a threat to diversity. It's an under-utilized source thereof. Give parents free rein and we'd be speciated a hundred ways in a half century. Now that would be real diversity!
Once we've developed the technology, some members of the elite will use reprogenetics whether we want them to or not. The only question that public policy can resolve is, how much access will everyone else have to such technology?
I wouldn't be so optimistic, kurt9. The Congress and Supreme Court have just said that it is a crime to abort a certain fetus in a given way, while it is allowed to abort the same fetus in a different way. What's the difference between that and legislating that it's "unnatural" to make a baby from selected chromosomes?
The rich can go overseas to get whatever they want. It'll be the religious ("against God's will") and left-wing ("Nazi supermen") agitators pushing for the bans, helped by the unease of the lower classes already struggling against the non-engineered upper classes of the day. Any reproductive mishaps will bring out the "Save the children!" forces. The middle class will be caught in the middle.
I agree the more affluent will travel to get what they want.
I think the biggest thing holding back germline genetic engineering is the inability to do it. We'll know what many genetic variations mean years before we can do much with that knowledge in embryos.
Once we know what the assorted genetic variations mean the desire to do genetic engineering will become intense. Boost the IQ of your kids by 50 points? Make them beautiful? Make them age more slowly? Give them amazing singing voices and great coordination? Make them so they don't get allergies, asthma, skin conditions, attention deficit, crooked teeth, or dozens of other undesirable traits? People will go crazy at the prospect of making kids with great features.
The ability to make superkids will become an enormous incentive to reproduce.
Dog of Justice,
Public policy cannot resolve the issue of access except to prohibit it for some population. The market and competition will make sure the technology is available to everyone at low cost.
For decades, the only undeniably effective medicines were aspirin and antibiotics. It's not like either of those were limited to a wealthy few. The Hollywood-style paranoia makes for interesting story lines if one suspends disbelief for an hour or two, but otherwise it is just nuts.
Interesting stuff. I'll also note that Razib is recently blogging about eugenics again, too. Must be something going around!
Do you think that people should have full freedom to create offspring lacking in a conscience? How about kids with no guilt, no empathy, no compassion, and nothing internal to cause them to behave ethically?
My own view: Such creatures are not rights possessing beings because they lack the attributes that make a rights-based society possible.
In an early Heinlein novel, _Beyond This Horizon_, he described a (fictional) reprogenetic technology that would be much more powerful than what we now do. The idea was to select egg and sperm separately, thus letting you choose among a much wider range of alternatives.
The obvious problem was how to determine the genetics of a single egg or sperm without damaging it. The ingenious solution was to take advantage of the mechanism by which egg or sperm is produced, in which the full set of genes is divided between two cells (yes, I'm oversimplifying a little). Destructively analyze one of them, destructively analyze an ordinary cell, subtract the results of the first analysis from those of the second, and what remains is in the complement cell--which you haven't touched.
Of course, this probably requires arranging for the final division to occur in vitro.
Randall Parker: those already get born, they're called "sociopaths". Chances are more parents would engineer that out, than engineer it in.
One of the consequences of free genetic tinkering would be that some individuals with human ancestry pass out of the current narrow range of what we consider human, and start to challenge who gets considered "people". Personally I think that would be a good debate to have.
Great idea from Heinlein. It makes sense as an approach given current directions of DNA sequencing R&D.
Nanopores for DNA sequencing (which big labs at Harvard and elsewhere are working on) and other nanotech approaches to DNA sequencing will eventually allow a single cell's DNA to get sequenced. The nanopore approach will sequence individual strands.
The nanopore approach will be cheap enough to allow examination of one member of many pairs. Just do it in parallel with thousands of cells until some wells in a microfluidic chip with built-in nanosequencer signal that they have the desired combination of chromosomes.
Given that one only has to identify which chromosomes are in each sperm or egg full sequencing for a member of every single pair won't be necessary, Though some recombination of DNA sections can occur between lined up chromosomes my guess is this is infrequent (though I'd like confirmation on that point).
The other part needed to do this is the ability to induce cells to become sperm and eggs in controlled conditions. That's already been done at least for sperm.
You comment that genetic selection should encourage more parents to have children, since it increases the chance of bearing a healthy, desireable baby. Yet it may have only a minor effect on the birth rate, since the pain, inconvenience, and hard work of bearing and raising a child is the more important deterrent.
Once we get past this tipping point, I'm sure we will make an artificial uterus as a way around all the complications.
Borrowed from the ever useful Wikipedia:
Primary research into the engineering of an artificial uterus was conducted at the Cornell University Center for Reproductive Medicine and Infertility, under Dr. Hung-Ching Liu. In the year 2002 Dr. Liu announced that she and her team had grown tissue samples from cultured endometrial cells removed from a human donor. The tissue sample was then engineered to form the shape of a natural uterus, human embryos were implanted into the tissue. The researchers found that the embryos correctly implanted into the artificial uterus' lining and started to grow. Dr. Liu's experiments were halted after six days, to stay within the permitted legal limits of in vitro fertilisation (IVF) legislation in the United States.
If anyone wants more intelligent and well adjusted children father them when you are 24 to 31. You don't have to get fancy just don't father any babies after your spermatogonia DNA has collected a large amount of copy errors etc. If there is any familial genetic disorders then screen all you want but remember to end your fathering of babies by 33. http://how-old-is-too-old.blogspot.com/