Researchers from Johns Hopkins University School of Medicine report in Nature Biotechnology that DNA methylation could mediate genetic risk of rheumatoid arthritis. As our sister publication GenomeWeb Daily News reports, the researchers profiled cytosine methylation marks, particularly focusing on CpG sites, in blood samples from about 350 rheumatoid arthritis cases and controls. The nine of their top 10 differentially methylated positions fell in MHC regions. And four CpG sites "showed an association between genotype and variance of methylation," the researchers write.
Johns Hopkins' Andrew Feinberg, the senior author of the paper, tells The New York Times that such epigenetic studies do not discount genetic susceptibility to disease. "Instead, it complements them," he says. "It is another arrow in the quiver."