GWAS and meta-analysis studies further identified loci associated with increased endometriosis risk, including SNPs in and around interleukin 1 alpha (IL1A) [106] and WNT family member 4 (WNT4) [99,107], encoding a protein involved in the WNT signaling pathway critical for the development of the female genital tract [82,108]. This evidence concerns the gene WNT4 and endometriosis.