SNPwatch: Genetic Variation Predicts Hepatitis C Treatment Success

SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.

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New genetic research may eventually help doctors identify those people with hepatitis C for whom the standard treatment, a grueling 48 week drug regimen, is doomed to fail.

In close to 1,700 people chronically infected with hepatitis C, researchers from Duke University found that those with two Cs at rs12979860 were more likely to have no detectable virus in their blood than those with TT at this SNP after 48 weeks of treatment with a combination of interferon and ribavirin.

The results, published online yesterday in the journal Nature, show that the virus was eradicated in close to 80% of people with two Cs, compared to only about 25% of those with TT. Treatment response in people with CT at rs12979860 was intermediate between the people with CC and TT.

Previously, one of the best predictors of treatment success has been ethnicity: people with European ancestry tend to respond better than African Americans. In the current study, 56% of European Americans were free of the virus after the treatment and follow-up period, while only about 24% of African Americans were.

The researchers determined that approximately half of this disparity is due to the differences in frequency of the C version of rs12979860 in different populations. Europeans are much more likely to be CC than African Americans. Other researchers have shown that Asians, most of whom are CC, are even more likely to become virus-free after treatment than Europeans.

Even though African Americans with hepatitis C respond poorly to treatment with interferon and ribavirin in general, 53% of those with CC at rs12979860 cleared the virus from their systems after treatment, compared to only 33% of Europeans with TT at this SNP.  As new drugs become available, information like this will be invaluable in determining what is likely to work best for each patient. Physicians will be able to base their prescription decisions on genetics instead of generalizations based on race, and patients will get medicines based on biology, not skin color.

(23andMe does not provide data for rs12979860 at this time.  A nearby SNP that was also significantly associated with hepatitis C treatment response was rs12980275.  Customers can check their data for this SNP using the Browse Raw Data feature. The A version of rs12980275 corresponds to the C version of rs12979860 and a better response to treatment. Because the two SNPs are not perfectly correlated, the magnitude of the effect of rs12980275 may not be the same as reported for rs12979860 and discussed above.)






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