In contrast, in endometriosis patients younger than 37 years (n = 176), combined homozygous and heterozygous mutant SNP (genotype AA+AG, 289Ser/Ser+289Ser/Gly) of HSD17B3 showed a significantly lower risk of endometriosis (P = 0.007; OR = 0.59) in comparison with the controls (n = 337) (Table 3). This evidence concerns the gene HSD17B3 and endometriosis.