This week in Genome Research, scientists at the University Hospital Regensburg in Germany have used a "novel approach that is based on the separation of a genome into methylated and unmethylated fractions" to scan for differential DNA methylation in human conventional CD4+ T cells and CD4+CD25+ regulatory T cells. They found more than 100 differentially methylated regions in mostly cell-type specific genes, the majority of which were found at promoter-distal sites.