Our SNPwatch posts here at The Spittoon are one of our most exciting features. They give our customers the opportunity to connect their genetic data to the newest discoveries, often within just hours of a study’s publication.

Looking ahead to 2009, we can only begin to imagine the exciting discoveries that will be made in genetics. In the meantime, here are a few of our favorite SNPwatches from 2008:

SNPs That Affect Drug Response
We reported on several studies this year that showed the importance of genetic variations in determining how different people react to certain medications.

• A report in Nature Genetics showed that some women with a particular version of a SNP in the NQO1 are less likely to survive breast cancer after treatment with the commonly used chemotherapeutic epirubicin.
• A study by the SEARCH Collaborative Group found that a version of one SNP is associated with an increased risk for myopathy (muscle pain and/or weakness) in people taking cholesterol-lowering drugs called statins.
• Mayo clinic researchers found that the weight loss drug sibutramine (Meridia) is effective only in people with specific versions of three different genes.
• And just this month we brought you news of three studies that showed that a genetic variant known to affect the metabolism of the anti-clotting drug clopidogrel (Plavix) also affects heart attack patients’ risk of a second major cardiovascular event.

Shared SNPs
Sometimes multiple conditions strike the same person or run in families. Several studies published this year showed that shared genetic risk factors may be part of the reason why.

• Obesity is a known risk factor for many cancers. Researchers found that a variant of adiponectin, a hormone released by fat cells, can increase the risk of developing colorectal cancer.
• Other researchers found variants that affect the risk of developing both type 1 diabetes and celiac disease, two autoimmune diseases that tend to cluster together. One of these shared variants is also associated with HIV resistance.
• Finally, a report published this month in the Proceedings of the National Academy of Sciences showed that a single genetic variant can make a person prone to greater indulgence in both smoking and drinking.

SNPs Associated with Risk Factors for Disease
Several studies this year looked beyond disease itself and instead found associations between SNPs and traits known to be risk factors for disease.

• One study found an association between several SNPs and fasting plasma glucose, a measure of how well a person’s body can control blood sugar levels – a process that goes awry in diabetes.
• Another research group reported SNPs associated with glycated hemoglobin levels, a measure of long-term blood sugar control and another factor associated with the risk of developing diabetes.
• The findings of three papers published in Nature Genetics roughly doubled the number of SNPs associated with blood levels of cholesterol and triglycerides, important risk factors for cardiovascular disease.
• And finally, in a study that looked at behavior instead of metabolic markers, researchers found that a variant in the FTO gene known to increase the risk for obesity affects food choices in children, pushing them towards foods denser in calories.

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In a recent post on his “Building Confidence” blog, 23andMe scientific advisor Russ Altman recounts an experience that should be familiar to 23andMe customers who regularly read The Spittoon. After reading a recent New England Journal of Medicine paper about a genetic variant associated with the development of side effects among people taking cholesterol-lowering statin drugs, Altman logged into his 23andMe account and checked his own genotype at the SNP in question.

“In about 30 seconds I went from reading an article of potential interest to checking my genotype and drawing a preliminary conclusion,” Altman wrote. “I must say it was quite quick, informative, even fun.”

Russ discovered that his genotype does not put him at elevated risk for statin-induced muscle soreness — not an earth-shattering realization, but one that he said might make him more comfortable with taking cholesterol-lowering drugs should he ever need them.

Now, most of us don’t scour the New England Journal looking for papers that might have relevance to our own health. That’s why The Spittoon publishes SNPWatch posts that announce the latest findings and identify the SNPs that 23andMe customers can use to see how that research might apply to them. In fact, we published a post on the statin-induced myopathy paper when it first came out back in July.

So if you’re a 23andMe customer who is interesting in learning about a particular topic, don’t forget to check The Spittoon as well as your account — because the latest research often appears here first.

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By lowering blood levels of “bad cholesterol,” or LDL, statins can lower the risk of heart attack and stroke. But the drugs are not without side effects — about one patient out of 10,000 experiences a form of muscle pain and/or weakness known as myopathy. A report published yesterday in the New England Journal of Medicine suggests that a variation in a gene previously linked to how the body processes statins may be partially to blame.

The SEARCH Collaborative Group, a large consortium of scientists studying the use of high simvastatin (Zocor/Lipex) doses in British patients who have previously had heart attacks, found that the C version of rs4149056 was associated with an increased risk of myopathy.

Out of about 6,000 people taking 80 mg daily of simvastatin (the usual dose is 20-40 mg), researchers identified 85 who either had myopathy or whose bloodwork suggested they were on the verge of developing it. When these people were compared to 90 people who were on high-dose simvastatin but had no signs of muscle problems, the researchers found that one C at rs4149056 increased a person’s odds of myopathy 4.9 times (compared to people with two Ts) and two Cs increased the odds 16.9 times.

(23andMe customers can check their data for rs4149056 through our Browse Raw Data feature. This SNP is one of 30,000 on the custom designed 23andMe SNP chip.)

The researchers also found an association between rs4149056 and myopathy in the Heart Protection Study, which compared about 10,200 people taking 40 mg of simvastatin with a similar number of people taking a placebo. In this case, however, the effect of the SNP was much smaller – each C increased the odds of myopathy only 2.6 times. Only 23 of the simvastatin-taking patients in this study had myopathy.

The myopathy experienced by both sets of patients in the New England Journal of Medicine report was mild and reversible. There is, however, a potentially fatal (but even more rare) form of muscle breakdown called rhabdomyolysis that has also been linked to statins. More research will be needed to investigate whether rs4149056 is also associated with rhabdomyolysis.

In addition to simvastatin, five other statins are available in the United States: lovastatin (Mevacor/Altocor), pravastatin (Pravachol/Selektine/Lipostat), fluvastatin (Lescol), atorvastatin, (Lipitor/Torvast), and rosuvastatin (Crestor). The authors of the study say that their findings likely apply to those drugs as well — myopathy is known to be a side-effect of all statins and variants in the gene where rs41419056 is found are known to affect blood levels of several statins.

Sixty percent of the myopathy cases observed in the study of patients taking 80 mg of simvastatin could be attributed to the C version of rs4149056. This suggests that avoiding giving high doses of statins to people who carry this version of the SNP could significantly reduce the incidence of myopathy, wrote Yusuke Nakamura in an editorial accompanying the study. Although he added, “further investigation is required to identify the optimal therapeutic approach.”

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