DNase I hypersensitive sites (DHSs). (A) Tissue-specific DHSs were predicted on the basis of DNase-seq data if chromatin accessibility was significantly higher in a given tissue than for the average over all cell types (ubiquitous DHS, black track). The vertical blue arrow indicates one of the top fetal-brain-specific DHSs more than 30 kb proximal to a promoter of GFRA1, a glial-cell-line-derived neurotrophic factor. Tissue types are color coded as in (B). (B) Hierarchical clustering of samples by DNase-seq profiles. The distance between samples was defined as 1-cor(x,y). Correlations were calculated between the log counts of DNase-seq reads in 200-bp non-overlapping windows. (C) Locations of cell-type-specific DNase I hypersensitive sites (CTS-DHSs) and ubiquitous DHSs. The top ranked CTS-DHSs fall mostly in intronic and intergenic regions. The majority of the top ubiquitous DHSs are in promoters. chr10, chromosome 10; CTS-DHS, cell-type-specific DHS; DHS, DNase I hypersensitive site; iPS, induced pluripotent stem cell; kb, kilobase.