Genetic Marker Predicts Response to Hepatitis C Treatment
Duke University Medical Center researchers report in Nature that the marker is a single letter change -- a C instead of a T -- in a segment of DNA near the IL28B gene.
The journal Nature published a study Aug. 16 identifying a genetic marker that predicts how well patients will respond to treatment for Hepatitis C, which affects an estimated 170 million people and is among the world's most common infections. It is the leading cause of liver transplants in the United States. Duke University Medical Center researchers said patients found to have a C instead of a T in a segment of DNA near the IL28B gene were significantly more likely to respond favorably to treatment than those lacking it.
"Eighty percent of those with the favorable response genotype eradicated the virus, while only about 30 percent with the less favorable response genotype did so," David B. Goldstein, Ph.D., director of the Center for Human Genome Variation in Duke's Institute for Genome Sciences & Policy and senior author of the study, said in a news release posted by the medical school. "With differences of that magnitude, patients considering therapy may want to know what their genotype is before they start treatment."
"This discovery appears to explain a large part of it. It is most certainly a triumph of translational medicine," added Dr. John McHutchison, M.D., associate director of the Duke Clinical Research Institute and study co-author.
They said the "good" genotype also explains previously puzzling differences in treatment response between population groups. "Because it appears significantly more often among Caucasian populations than it does among African populations, we feel it explains much of the difference in response rates we see between African-Americans and those of European ancestry," Goldstein said. "This tells us that individual genetic makeup is much more important determinant of response to treatment than is race or ethnicity."
Having the "good" genotype also meant there was lower viral load -- a measure of how much virus circulated in the patient before treatment -- than in patients without it, they reported. Some people with Hepatitis C do not require treatment, but those who do are given 24 or 48 weeks of interferon and an antiviral. This clears the infection in fewer than half of the people with the most common form of Hepatitis C.
The study was funded by the Schering-Plough Research Institute.