We tested for enrichment in the ADHD h2SNP of variants located in cell type-specific epigenetic peaks by examining the overlap of common genetic risk variants with open chromatin from a DHS (DNase I hypersensitive sites) study profiling major human cell types31 and an scATAC-seq (single-cell assay for transposase accessible chromatin)32 study using an LD-score partitioned heritability approach84. All regions of open chromatin were extended by 500 bp in either direction. The broad MHC region (hg19 chr6:25–35Mb) was excluded due to its extensive and complex LD structure, but otherwise default parameters were used for the algorithm. We applied Bonferroni correction (correcting for 23 cell types), and results below P = 0.0022 were considered significant.
