IL1B and endometriosis: A known dysmenorrhea signal near NGF replicated in our data (rs12030576; P = 1.1 × 10−19) and was associated with RP4-663N10.1 expression, a putative lncRNA enhancer of NGF, while a novel dysmenorrhea signal in the IL1 locus (rs80111889; P = 1.9 × 10−16) contained SNPs previously associated with endometriosis, and GWAS SNPs were most significantly associated with IL1A expression.