IL1A and endometriosis: Previous studies using genome-wide association (GWA) analysis have identified susceptibility genes for endometriosis in chromosome 2.17, 18, 20, 26 Adachi et al17 showed that four of the top five SNPs were in and around interleukin 1α (IL1A) at 2q13, which might be a functional candidate gene for endometriosis.