Integration of genome-wide association study and expression quantitative trait locus mapping for identification of endometriosis-associated genes

To determine whether genetic predisposition to endometriosis varies depending on ethnicity and in association with expression quantitative trait loci (eQTL) in a Taiwanese population. We conducted a genome-wide association study (GWAS) and replicated it in 259 individuals with laparoscopy-confirmed stage III or IV endometriosis (cases) and 171 women without endometriosis (controls). Their genomic DNA was extracted from blood and evaluated by the GWAS of Taiwan Biobank Array. Novel genetic variants that predispose individuals to endometriosis were identified using GWAS and replication, including rs10739199 (P = 6.75 × 10⁻⁵) and rs2025392 (P = 8.01 × 10⁻⁵) at chromosome 9, rs1998998 (P = 6.5 × 10⁻⁶) at chromosome 14, and rs6576560 (P = 9.7 × 10⁻⁶) at chromosome 15. After imputation, strong signals were exhibited by rs10822312 (P = 1.80 × 10⁻⁷) at chromosome 10, rs58991632 (P = 1.92 × 10⁻⁶) and rs2273422 (P = 2.42 × 10⁻⁶) at chromosome 20, and rs12566078 (P = 2.5 × 10⁻⁶) at chromosome 1. We used the Genotype-Tissue Expression (GTEx) database to observe eQTL. Among these SNPs, the cis-eQTL rs13126673 of inturned planar cell polarity protein (INTU) showed significant association with INTU expression (P = 5.1 × 10^–33). Moreover, the eQTL analysis was performed on endometriotic tissues from women with endometriosis. The expression of INTU in 78 endometriotic tissue of women with endometriosis is associated with rs13126673 genotype (P = 0.034). To our knowledge, this is the first GWAS to link endometriosis and eQTL in a Taiwanese population.