a, Top: Profiles for nine chromatin marks (grayscale) are shown across the wntless (WLS) gene in four cell types, and summarized in a single chromatin state annotation track for each (colored according to b). WLS is poised in ES cells, repressed in GM12878 cells, and transcribed in HUVEC and NHLF. Its TSS switches accordingly between poised (purple), repressed (grey) and active (red) promoter states; enhancer regions within the gene body become strongly activated (orange, yellow); and its gene body changes from low signal (white) to transcribed (green). These chromatin state changes summarize coordinated changes in many chromatin marks; for example, H3K27me3, H3K4me3 and H3K4me2 jointly mark a poised promoter, while loss of H3K27me3 and gain of H3K27ac and H3K9ac mark promoter activation. Bottom: Nine chromatin state tracks, one per cell type, in a 900kb region centered at WLS summarize 90 chromatin tracks in directly-interpretable dynamic annotations, showing activation and repression patterns for 6 genes and hundreds of regulatory regions, including enhancer states. b, Chromatin states learned jointly across cell types by a multivariate HMM. Table shows emission parameters learned de novo based on genome-wide recurrent combinations of chromatin marks. Each entry denotes the frequency with which a given mark is found at genomic positions corresponding to the chromatin state. c, Genome coverage, functional enrichments, and candidate annotations for each chromatin state. Blue shading indicates intensity, scaled by column. d, Box plot depicts enhancer activity for predicted regulatory elements. 250bp-long sequences corresponding to strong or weak/poised HepG2 enhancer elements, or GM12878-specific strong enhancer elements were inserted upstream of a luciferase gene and transfected into HepG2 cells. Reporter activity was measured in relative light units. Robust activity is seen for strong enhancers in the matched cell type, but not for weak/poised enhancers or for strong enhancers specific to a different cell type. Box-and-whiskers indicate 5th, 25th, 50th, 75th and 95th percentiles.