While some of the people with Hepatitis C suffer throughout the life and develop serious liver disease, including cancer, others are able to defeat the infection and get rid of the virus with no treatment.
"If we knew why some people got rid of the disease on their own, then maybe we could figure out ways to help other people who didn't. Or maybe even help prevent infections entirely," Nature quoted Dr. David Thomas as saying.
In a previous study, researchers had found a variation in a single chemical of DNA, known as a single-nucleotide polymorphism, or SNP, near the IL28B gene, which while poorly understood, is thought to help the immune response to Hepatitis C viral infection.
People infected with Hepatitis C, who carried the C/C variation SNP near their IL28B gene, were found more likely to respond to hepatitis C treatment, which can rid some patients of the virus.
Thus, the researchers in the current study wondered if the C/C variation-as opposed to the C/T or T/T alternatives-also played a role in some peoples' ability to get rid of the virus without the help of medication.
So, they assembled information from six different studies that had over many years collected DNA and Hepatitis C infection information from people all over the world.
Then, the team analysed DNA at the IL28B gene from a total of 1008 patients- 620 persistently infected and 388 who had been infected but no longer carried any virus.
DNA analysis revealed that of the 388 patients who no longer carried virus, 264 have the C/C variation.
"This is the strongest clue to date to understanding what would constitute a successful immune response. We don't yet know the significance of this C variant, but we know we need to do more work to find out what it means and whether it might be helpful to halting the disease," said Thomas.
The researchers also noticed an intriguing trend- the C/C variant does not appear equally in all populations.
"We wonder if this SNP also explains some of the genetic basis for the population difference of Hepatitis C clearance. It's been reported that African-Americans are less likely to clear the disease than Caucasians," said Dr. Chloe Thio, associate professor of medicine.