Dr. Zoltan Kutalik, from the Department of Medical Genetics, University of Lausanne, Switzerland, told delegates that individuals with this change, in a gene encoding for the antiviral cytokine (cell-signalling molecule) interferon lamda, reacts less well to treatment. This knowledge could spare them the unpleasant side effects of a therapy which most likely would have little benefit for them, he says.

Hepatitis C is a serious liver disease, normally contracted through drug use, blood transfusion or sexual transmission. About 10% of all patients have no identifiable source of infection. The virus produces chronic infection in around 80% of infected individuals, and half of these do not respond to existing therapies. Current treatment involves a combination of an interferon and the antiviral medication ribavirin. Side effects are common and can be serious to the extent that some people are unable to continue to work.

The fact that people respond so differently to the same treatment is usually because a genetic variation in the non-responders is, via complex genetic pathways, inhibiting the effects of therapy. "The Lausanne University Hospital (CHUV) has a large cohort of Hepatitis C patients seen at the hospital over many years", said Dr. Kutalik, "so this provided the opportunity for us to do a genome-wide association study on 1362 of them to see if we could track down any differences relating to patients' failure to respond to therapy."

Genome-wide association studies look at variations across the entire genome of individuals to look for genetic associations with well-defined traits, including why some people get a particular disease and condition as well as why they might react or not to therapy for it. In this case, approximately half of the patients studied had responded successfully to therapy, giving the scientists the opportunity to compare their genomes with those from patients who had not responded.

(Medical News Today)

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