Are Genetic Tests Useful Part 3

I'll let Kevin reveal what he wants to about his results for disease; what I'd like to share right now is how we fared on those genetic variations that might be called recreational or just plain bizarre. These include gene markers for wet or dry earwax, the sprinter's gene, and a marker that increases one's chance of becoming a heroin addict.

You 2.0 Series Comparison Shopping for Your Future Part 1: Personal genetic tests are proliferating; some are even online. Do they really tell you anything? I'm Doomed. Or Not. Part 2: Commercial genetic tests tell me I have high, medium, and low risk of heart attack. What gives?

I'm not kidding. Skip ahead to the chart of results below, and you'll see that both Kevin and I are at high risk of drug addiction, according to a 2004 study conducted in Sweden. Here is what 23andMe says about this test:

In the brain, heroin is converted to morphine, an opioid painkiller. Morphine acts by signaling through a receptor encoded by the gene OPRM1. Different versions of the OPRM1 gene are thought to affect how much morphine one needs to feel a given effect. This study of 139 heroin addicts (primarily Swedes) and 170 nonaddicts found that people with one or two copies of the G version of the SNP rs1799971 have almost 2.9 times the odds of being a heroin addict.

Here is how Kevin's results are presented on his 23andMe site:



A 2.9 times normal risk factor is relatively high, though even 23andMe gives the validity of this data only two stars (out of four) because the researchers tested only about 300 people. That gives these results a very low statistical power to predict whether others, such as Kevin and myself, will really become addicts. 23andMe calls such findings preliminary, which makes one wonder why such a test is even included. 23andMe offers the following caveat:

Preliminary Research This is a Preliminary Research topic and includes results of studies that still need to be confirmed by the scientific community. It also includes topics where there may be contradictory evidence. The results of these studies are not conclusive.

Just for the record, Kevin and I are not addicted to heroin.

Most of these "fun" or oddball traits appear only on 23andMe, which features results for 60 genetic traits, compared with 26 for DeCodeMe and 17 for Navigenics (these numbers vary slightly according to sex).

23andMe has close ties to Google and tends to treat nearly all genetic results as equal—that is, it lists and describes earwax alongside age-related macular degeneration and colorectal cancer. Each of 60 traits it offers is accompanied by detailed information about the trait, studies, risk factors, and links to more information.

At the opposite end of the spectrum is Navigenics, which offers only information on medical conditions—no bitter taste or heroin addiction. In between the two is DeCodeMe, which offers mostly disease information but throws in some recreational results—bitter taste, for instance.

23andMe and DeCodeMe also provide results for ancestral data that traces a customer's genetic lineage back to migration patterns of early humans coming out of Africa 50,000 years ago and spreading out to Asia, the Americas, Oceania, and Europe.

DeCodeMe tracked my DNA to the most common markers for Western Europeans, with the closest ethnic association through my father (my Y chromosome) connecting me to Scotland—where my ancestors do come from.

Through my mother (my mitochondrial DNA), I am also associated with a band of humans that emerged in Europe 15,000 years ago. Luminaries from this haplogroup—a cluster of people sharing similar ancestral patterns of DNA—include Saint Luke, Marie Antoinette, and Warren Buffett.

Kevin, who is of Irish ancestry, belongs to the same "tribe" as I do through our fathers, but his mother's lineage links him with a group that also includes Kurds, Druze, and Ashkenazic Jews.

For many other attributes, Kevin and I tested the same, for better or for worse. Both of us have a high probability of having blue eyes and of being lactose tolerant, things we knew even without a genetic test.

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DNA Traits Comparison: David Ewing Duncan and Kevin Kelly

Trait	Gene Marker	Risk	D.E.D.	K.K.	Risk Factor
Alcohol flush*	rs671	A	GG	GG	Normal/No flush
Avoiding errors	rs1800497	A	GG	GG	Learns to avoid errors
Blue eyes*	rs12913832	G	GG	GG	Blue eyes
Bitter taste*	rs713598	C	CC	CG	No bitter taste/ Bitter taste
Caffeine metabolizer	rs762551	C	AA	AC	Fast/Slow
Earwax	rs17822931	C	CC	CC	Wet
Heroin addiction	rs1799971	G	AG	AG	Substantially higher risk
Endurance (or Sprint)	rs1815739	T	TT	CT	High endurance/ Sprinter
Intelligence	rs363050	G	GG	GG	Lower I.Q. (3 points)
Lactose intolerance*	rs4988235	G	AG	AA	Lactose tolerant
Novelty Seeking**	rs6280	T	CT	TT	Med. Risk-Taking/High Risk

^{All traits are from 23andMe.com, except:
*Also on DeCodeMe.com
**Not on either site}

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Also, neither of us have a variation that causes some people's cheeks to become flushed when they drink alcohol, and both of us have a proclivity to learn from our mistakes—a useful thing for writers and geneticists.

Less attractive is a DNA marker linking us to a reduction of three points in our I.Q. scores, whatever that means.