To detect genome-wide functional and tissue-specific epigenomic enrichments, we performed enrichment analyses by heritability stratification using Linkage Disequilibrium Score Regression (LDSC v1.0.0), implemented in the LDSC software. Annotation-stratified LD scores were estimated using dichotomized/binary annotations, 1000 Genomes Project samples with European ancestry, and one million base-pair LD windows by default. LDSC then determines functional enrichment of the GWAS traits by partitioning heritability according to the variance explained by the LD-linked SNPs belonging to each functional category22. Statistical enrichment was defined as the ratio between the percentage of heritability explained by variants in each annotated category and the percentage of variants covered by that category. A resampling approach was used to estimate standard errors22.
