HLA-G and endometriosis: The reason why one polymorphism, rs1632947:GG genotype in the promoter region, increasing expression of HLA-G (Ober et al. 2006), seems to protect against endometriosis, whereas 14 bp deletion in 3′UTR (rs371194629), also increasing HLA-G expression (Verloes et al. 2017), had no effect, needs explanation by further experiments.