Gina Kolata writes in the NYT:
Study Says DNA's Power to Predict Illness Is Limited
“The punch line is that this sort of personalized medicine will not in any way be the most important determinant of patient care,” said Dr. Bert Vogelstein of Johns Hopkins, who, with his colleagues and his son Joshua, analyzed the power of sequencing all of a person’s DNA to determine an individual’s risk of disease. The study, published online Monday in the journal Science Translational Medicine, involved data from 53,666 identical twins in registries from the United States, Sweden, Finland, Denmark and Norway. The registries included data on 24 diseases, telling how often one twin, both or neither got a disease.
Since identical twins share all of their genes, the investigators could ask to what extent genes predict an increased chance of getting a disease. Using a mathematical model, they reached an answer: not much. Most people will be at average risk for most of the 24 diseases.
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17 comments:
re: Porsafillo Preschool Academy and headmaster/mistress Unsinn.
C'mon, Steve, Unsinn means nonsense in German. Sounds like a hoax.
Mike Eisenstadt
It's not "my genes evolved to kill me" but "my genes will accept faults that I won't, since they can jump ship and I can't."
I think personalized medicine in total will be a big deal, but I don't think DNA analysis will play as much as part of it as people expect. I mean, the study of how genes get expressed is a big deal that makes the sorts of genetic analyses that we can do now very ineffective.
The real benefit of personalized medicine will be just collecting lots and lots of data on people, and using that data to diagnose people and learn about human biology. Even just getting people to realize things like "depression is a symptom, not a disorder" will represent a major advance.
data from 53,666 identical twins in registries from the United States, Sweden, Finland, Denmark and Norway... Most people will be at average risk for most of the 24 diseases.
If you assume that identical twins [who have a history of having been studied in major medical experiments] are a good statistical predictor for people who do not necessarily have an identical twin [and who do not necessarily have a history of having been studied in any major medical experiments].
And if you assume that - for instance - data on people from United States, Sweden, Finland, Denmark and Norway is a good predictor, of, say, hypertension or diabetes or sickle-cell anemia in Americans with significant West African ancestry.
And if you assume that blah blah blah blah blah blah blah...
But any genetic defect that doesn't show up until after reproduction won't affect evolution. We have plenty of fatal genetic dispositions, cancer, Alzheimers, that don't show up until after our reproductive years. Few people die of natural causes between five and forty.
What is the point of this post?
Wmarkw:
It been shown quite a few times that selection still operates after reproductive age, which for men is a bit more than forty. Most of the diseases with more or less purely genetic cause tend to hit in the seventies or later.
I agree with the idea that your genes didn't evolve to kill you, but I would like to see the actual study before saying much else. That article is a perfect example of the miserable state of science reporting: there was almost no real data about the study in the article and it's hard to draw any firm conclusions about the quality of the researchers' interpretations.
But we do know that different population groups have different disease risks. So the important word here is "personalized."
But we do know that different population groups have different disease risks.
Not to mention specific individuals within specific populations.
Can anyone say "Tay Sachs"?
Or, as above, "Sickle Cell Anemia"?
Or, God forbid, "Cystic Fibrosis"? [Now there's a death sentence for ya' - right about at the age of twenty - when a cave man would already have fathered two or three children.]
PATHOGENS!
Gina Kolata
Lol. If she's not married, her parents had a sense of humor.
Properly, the title should be:
"Study Says Our Ability to Interpret DNA Is Limited". Particularly with the primitive models like the one employed in the paper in question.
Unsinn means nonsense in German. Sounds like a hoax.
Das stimmt.
Wmarkw:
Without decent technology (safe water supplies, sewers, vaccines), something like 50% of the population dies off before reaching reporductive age. The fact that so few kids die young now is not due to genes (other than the ones for intelligence and cooperation).
There are probably selection effects for older people, but they're attenuated a great deal by the fact that until very recently, most people didn't make it to 60 in any shape to help anyone. One compound fracture, infected wound, case of pneumonia, bad allergic reaction, etc., was usually going to kill you until we got around to inventing decent medical science some time in the last 150 years or so. Everyone y know over 60 is probably on a couple medicines and has had at least one injury or illness that would have threatened their life without modern medicine. Lots of people are walking around with diabetes or serious asthma or epilepsy, or after heart attacks or cancer or serious infections or emergency appendectomies. Feww would be if they'd had to count on the medicine available in, say, 1800 in Paris, and still fewer in hunter gatherer land or small agricultural village with iron tools land.
The result is that genes that helped you get from 60 to 70, even if that would have helped your offspring, had almost no fitness effect--hardly anyone with those genes lived long enough to benefit from them.
The chance of somebody who made it to 15 making it to 60 wasn't too bad. Think of guys who became famous fairly young, like the Ninja Turtles: Leonardo made it to his late 60s, Michelangelo to his late 80s, Donatello to about 80, and Raphael only to 37. They were probably healthier than average, and there is a selection effect (Massacio might have made it to Ninja Turtlehood over Donatello if he hadn't died in his 20s), but still ...
Of course your genes (some of them) evolved to kill you. Assuming you dodge disease and accidents, you are turned off at the end by very definite biological processes. This is not the same as "wearing out." Wearing out is what happens to your car. Why don't we live as long as those 1,000-year-old trees? Because our genes evolved to give us shorter life spans, that's all.
Cystic fibrosis is going to kill you as an infant or toddler without modern medicine.
And nearly all men with CF are sterile - no vas deferens, and women have reduced fertility - thickened cervical mucus.
But one copy of the gene might have protective effects against diarrhea or TB.
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