Hepatitis C affects 170 million people worldwide and is the leading cause of cirrhosis of the liver in North America. Treating the disease is particularly grueling: a forty-eight-week course of the antiviral drugs interferon and ribavirin is usually prescribed, though effectiveness varies widely depending on a patient's race.
Research conducted at the Institute for Genome Sciences & Policy's Center for Human Genome Variation has shown why the treatment is more successful in those with European ancestry than in African Americans.
The reason, researchers say, is a single DNA site, known as interferon-lambda-3. Here, patients possessing a CC allele type of gene respond much better to the standard treatment than do those with a TT allele. The CC allele is present in 55 percent of European Americans but only 25 percent of African Americans.
The CC allele causes cells to produce more interferons than the TT allele, though the mechanism for why this is so has yet to be discovered.