In all endometriosis patients (n = 300), a univariate analysis for the Gly289Ser (G/A) polymorphism of 17β-hydroxysteroid dehydrogenase III (HSD17B3) revealed that only heterozygous mutant SNP (genotype AG, 289Ser/Gly) of HSD17B3 showed a significantly decreased risk of endometriosis (P = 0.03; OR = 0.7) as compared to the controls (n = 337) (Table 2). The gene discussed is HSD17B3; the disease is endometriosis.