CD4 and type 1 diabetes mellitus: To determine if noncoding, T1D-associated variants have a gene regulatory effect, we first identified SNPs in linkage disequilibrium using 1,000 Genomes data, and then determined if they reside at candidate enhancer elements in activated CD4+ T cells using previously generated chromatin maps of H3K4me1 (11) (Figure 1A), which is known to mark enhancers (18).