accessibility-aggregationlisted

## When to Use - User wants to combine ATAC-seq or DNase-seq peaks across multiple experiments for a tissue - User asks "where is chromatin accessible in my tissue?" or "build an open chromatin map" - User needs to merge accessibility data from different labs, donors, or platforms (ATAC vs DNase) - User wants a comprehensive set of open chromatin regions for regulatory element discovery - Example queries: "aggregate ATAC-seq peaks for pancreas", "combine DNase-seq across donors", "find all accessible regions in liver" # Aggregate Chromatin Accessibility Peaks Across Studies Build a comprehensive map of open chromatin for a tissue/cell type by merging ATAC-seq and/or DNase-seq narrowPeak files from multiple ENCODE experiments. ## Scientific Rationale **The question**: "Where is chromatin accessible in my tissue?" Like histone marks, chromatin accessibility is a **detection question**. An open chromatin region detected in one donor but not another is still a real accessible site — individual variation, sequencing depth, and technical factors explain absence. We want the **union of all detections**. ### ATAC-seq vs DNase-seq Both measure open chromatin but with different biases: | Property | ATAC-seq | DNase-seq | |----------|----------|-----------| | Method | Tn5 transposase insertion | DNase I hypersensitivity | | Input required | ~50K cells | ~1M cells | | Resolution | High | High | | GC bias | Moderate (Tn5 preference) | Low | | Mitochondrial reads | High (filter ne