bookofjoe

BehindTheMedspeak: Why doesn't DNA profiling work?

Sharon Begley, the superb Wall Street Journal science columnist, addressed the question in her July 7 column.

Long answer short: Because the future remains — at least as yet — unknowable.

Since genes must act in the real world — not in a laboratory vacuum with variables held to a minimum — unpredictable life events and circumstances govern the expression, or lack thereof, of our encoded genetic messages.

Commenting on why some individuals who have a gene associated with violence and aggression show no heightened aggression, Dr. Stephen Suomi of the National Institutes of Health, whose research centers on this subject, said, "If you have a good mother, it doesn't make a damn bit of difference which gene you have. Good mothering acts as a buffer."

Here's the column.

Life Events Thwart Scientists' Attempts To Draw DNA Profiles

Genetics might not seem to have a lot in common with birding, but the fields share one pesky little problem.

Birders are wont to fight over whether someone saw what he claimed. ("It's an ivory-billed woodpecker!" "No, you fool, it's a pileated!") Geneticists on the trail of genes for human behavior have a 15-year record of finding DNA that increases the likelihood that a person will be neurotic, depressed, schizophrenic, a thrill seeker ... only to see other scientists claim their research shows that the gene is no more common in people with that trait than in anyone else.

Now there is a glimmer of an explanation for why such "failures to replicate" are common in behavioral genetics: The same gene produces different traits in different people.

Contrary to traditional understanding, genes don't lead inevitably to traits. Instead, says Darlene Francis of the University of California, Berkeley, scientists are discovering that "there is this intervening variable called life," as she told the International Congress of Neuroendocrinology last month in Pittsburgh.

Life definitely intervenes between a gene called MAOA and the extreme aggression that researchers claimed it causes. In the late 1980s, a number of men in several generations of a large Dutch family were found to carry a mutation in the MAOA gene that made it inactive. They all had a long rap sheet of rape, attempted murder and arson. MAOA became known as the "violence gene," headlines warned of "a violence in the blood," and there was talk of screening everyone to identify carriers.

The link between MAOA and aggression made biological sense. MAOA breaks down brain chemicals, including serotonin. It comes in two forms, short and long. The short form, which about one-third of people have, can't do the breaking down as efficiently as the long form, disrupting the balance of neurotransmitters in the brain. The result was thought to be higher levels of aggression, as measured by a surge in activity in the brain's fear region -- the amygdala -- at the sight of an angry face. That might explain the hair-trigger tempers in that Dutch family.

In a study of 531 U.S. men, however, the violence gene didn't live up to its billing. When psychologist Stephen Manuck of the University of Pittsburgh analyzed men carrying the short form of the MAOA gene, he told the ICN meeting, only those who held antisocial attitudes, who received little parental affection as kids and whose fathers had low levels of education also had a history of aggression. Presumably, dad's low education is a marker for other traits, perhaps how he treats his kids.

"Men with none of these risk factors for aggression had the same low level of lifetime aggression even if they had the short form of the MAOA gene," says Prof. Manuck. That suggests the gene isn't associated with aggression per se, he says, but instead is tied to putting the brakes on tendencies that already are present for other, often environmental, reasons.

Another gene follows the same pattern. It makes a serotonin receptor in the brain and also comes in two forms. One form, which creates a slightly different version of the serotonin receptor, is associated with antisocial behavior and aggression, but only in men whose fathers never finished high school, Prof. Manuck finds. Again, dad's education is undoubtedly a proxy for something that acts directly on his children.

It should have been clear that the short form of the serotonin-receptor gene is no Jack-the-Ripper DNA. Some two-thirds of Japanese carry the short form, but that population isn't known for violence. That suggests something in Japanese culture or child-rearing practices defuses the gene's supposed effects, Prof. Francis speculates.

Snatching children from their parents so scientists can raise some one way and some another way is generally frowned upon, so researchers study the next best thing: monkeys. In research using rhesus monkeys, Stephen Suomi of the National Institutes of Health leaves some newborns with their mothers but moves others to be reared by other young monkeys. Like people, rhesus monkeys have either a long or short serotonin-transporter gene.

"Rhesus monkeys with the short form and who are reared by their mother show no heightened aggression," Dr. Suomi says. "The gene is associated with aggression only if they have a history of childhood abuse or neglect," just as in the humans Dr. Manuck studied. "If you have a good mother, it doesn't make a damn bit of difference which gene you have. Good mothering acts as a buffer."

There is a strange aspect to behavioral genetics. Both researchers and laypeople are smitten by the notion of genetic determinism, despite the drumbeat of discoveries like these. Why the DNA worship?

"Even for scientists, it's much easier to say this gene is related to this behavior," says Prof. Francis. "People have a hard time understanding that experience and social factors are transduced into biology. ... It's a radical idea." Figuring out how experiences reach down into the double helix is this field's next big challenge.

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Just as scientists are now learning, via functional MRI studies, that psychotherapy causes observable structural changes in the brain, so with behavioral genetics.

Once upon a time molecular biologists would have laughed at you if you'd suggested that nurture could alter the functional expression of your DNA.

They aren't laughing any more.

Could Lysenko have been right?

Tip Toes — 'Stop slipping out of your shoes'

When you're wearing serious heels it can be a problem.

From the website:

Tip Toes™ — Stop Slipping Out of Your Shoes

Soft petal-shaped cushions stop feet from sliding forward in your favorite shoes.

They protect the delicate ball-of-foot area from pain, irritation and friction while preventing blisters and calluses.

Self-adhering pads are virtually undetectable inside shoes.

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One pair, in Buttercup (above), Black or Silver cost $7.

Rare Films on YouTube

Go to www.greylodge.org/gpc and choose "link dump" under "Categories" (above).

You will find "Categories" in the left-hand column after scrolling down a bit.

[via Ian Mount and the Wall Street Journal]

Twist Board — Official Treadmill Substitute of the Chubby Checker Fan Club

Do Tom Niccum, Dr. Jim Levine and Liz Ditz know about this?

From the website:

Twist The Inches Away!

Slim your waist, thighs and hips with this easy and fun-to-use Twist Board by Bally Total Fitness®.

Compact and durable, it features 2 discs that roll on precision-guided ball-bearings.

Provides a low-impact aerobic workout.

Supports up to 250 lbs.

Includes fitness guide.

Weighs only 16 oz.

Ideal for travel.

10" diameter.

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Because not everyone's crazy about spending a day at the office on yet another treadmill.

One's more than enough, what?

$12.

Metroblogging.com

What's this?

From the redoubtable Sean Bonner comes this new website, featuring posts from bloggers in 48 cities (listed above) around the world.

Take a cheap trip from the comfort of wherever.

Belt Hanger — 'Holds up to 40 belts in 3 inches of space'

Can your belt hanger do that?

Do you even have one?

Didn't think so.

From the website:

Belt and Accessory Hanger with Rings

This belt hanger is made of high quality nickel-coated steel.

The belt and accessory organizer hangs from a standard closet rod.

The unique space saving design holds up to 40 belts in 3 inches of closet space.

The 5 openable ring holders allow you to sort items by color or style and permit quick selection and removal.

7"W x 11"H x 3"D.

$4.99 (belts not included).

Global computer keyboard layouts, organized by language and region

Which keys do what on computer keyboards in non-English-speaking countries?

Find out here.

"Click the number after each country to see an interactive map of its keyboard," wrote Rob Pegoraro in the July 9 Washington Post.

Luma Tweeze — Pocket-sized magnifying tweezers with built-in LED light

A lot going on in the eyebrow space.

From the website:

Luma Tweeze™

Luma Tweeze lights the way to perfectly shaped brows!

Pocket-sized magnifying tweezers have a built-in LED light to help you see the tiniest of stray hairs, so tweezing is easier and safer.

They're ideal for splinter removal and other delicate tasks, too!

Includes button-cell batteries plus bonus eyebrow grooming brush.

On/off switch.

4" L.

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Makeup professionals will tell you that the single fastest, cheapest way to improve your appearance is to have your out-of-control eyebrows re-engineered so that they perfectly fit your face.

"As Seen On TV" so you know it must be all good.

$9.98.