It was nice while it lasted. But the idea that all the world's people are 99.9 per cent genetically identical -- that a mere sliver of DNA separates a Dolly Parton from a Dalai Lama -- is untrue.
An international research team has overturned the harmonious message that flowed from the Human Genome Project in 2000 and discovered more DNA differences exist among people than the experts expected.
It was bound to happen. All those people delighted that we aren't unique are going to have to find something new to gloat about, I suppose, because we're a lot more complicated than they were giving us credit for.
Using new technology to study the genomes of 270 volunteers from four corners of the world, researchers have found that while people do indeed inherit one chromosome from each parent, they do not necessarily inherit one gene from mom and another from dad.
One parent can pass down to a child three or more copies of a single gene. In some cases, people can inherit as many as eight or 10 copies.
In rare instances a person might be missing a gene.
Yet despite these anomalies, they still appear to be healthy -- countering the notion of what doctors have deemed "normal" in genetics.
The work highlights how DNA helps to make each human unique, hinting that a towering basketball player, for example, might boast extra copies of a growth gene or that a daughter really might be more like her dad.
That's amusing to me, since I've known for years that I'm just like my dad, and I bet a lot of other women have thought the same thing.
Unfortunately, the research has a darker side.
It suggests that some medical tests --such as prenatal scans -- may have incorrectly flagged these kinds of genetic quirks as signs of potential defects).
Remember (how can anyone forget) the abortion discussion that's been going on (and on and on and on) for the last week or so? The one that discussed this study by the Alan Guttmacher Institute which included a table of reasons women get abortions? "Possible problems affecting the fetus" was a reason given by 13 women. What if those women had depended on the type of prenatal exams that "may have incorrectly flagged these kinds of genetic quirks as signs of potential defects"? That seems rather problematic to me.
Now granted, the number of women who cited fetal abnormalities as their reason for having an abortion was quite small by comparison with, say, the women who said they were unmarried (42), the number one reason given. But still, wouldn't even one child have been worth it? Probably not to pro-choicers.
Each time I was pregnant, they asked me if I wanted to do these prenatal scans. Each time, I told them "no," not because the results wouldn't have been informative in some way, but because the information wouldn't have changed my mind. I have to wonder how many women chose abortion on the basis of these tests. Now that's sad.
Each time, I told them "no," not because the results wouldn't have been informative in some way, but because the information wouldn't have changed my mind.
ReplyDeleteThe neat part about being a pro-choicer, is that we support your right not to know, other people's rights to know, and the pregnant woman's right to make decisions based on information available.
See how simple it is when you decide that women are human beings and are entitled to full human rights, pregnant or not pregnant?
Pro-choicers believe women have the right to make decisions about our own bodies - ideally, to make informed decisions. You believe women shouldn't have the right to make decisions, and therefore argued yourself into remaining ignorant so that you couldn't. Sad, really.
What's sad is that you can't possibly comment on the idea that faulty results from prenatal tests result in healthy babies being aborted. And that you have to work so hard at it. That's sad.
ReplyDeletefrom what i understood, prenatal tests does not rely solely on genetic probability to identify fetal conditions. that would make no sense. you can hear a heart murmur, you can see a brain growing outside the head. what spefically are we talking about?
ReplyDeleteI don't think they're talking about the sorts of defects that might be visible in an ultrasound or verifiable with a stethoscope. The article specifically referenced Down's Syndrome as an example of an abnormality that could be misdiagnosed by depending on prenatal testing.
ReplyDeleteObviously, if it were a defect that one could see or hear, it might be a different story for the expectant parents. But, for instance, the alpha fetal protein test is done at about five months gestation, and I know that that test is used to determine Down's Syndrome among other things.
can you explain that to me a little? it's a test that has to be done during gestation, i.e. it's not something that you can tell simply by looking at each parent's history and combining the observations, correct?
ReplyDeleteso if it is more directly relevant to the fetus than simply doing a punnet-square of the parents (for example), then where does the margin of error that you mention lie?
According to the article, researchers are discovering that we can get multiple copies of a gene from one parent or the other, and that sometimes a person is missing a gene, yet still appears healthy.
ReplyDeleteIn various tests such as the alpha-fetalprotein test, the technician is checking for certain genetic markers we associate with Down's Syndrome. If, as the author of the original story suggest, one can be missing a gene and still be healthy or have multiple copies of a gene and still be healthy, all our assumptions about genetics for prenatal screening could be incorrect.
Here is an explanation from Labcorp about prenatal testing:
http://www.labcorp.com/genetics/prenatal_genetic_testing/index.html
From experience, I can tell you that some pregnant women can rely heavily on these tests in determining whether they want to continue their pregnancies or not. I consider it to be an absolute tragedy that these tests aren't nearly as accurate as most of us have assumed they are.