BACKGROUND: Endometriosis, an estrogen-dependent disease, is believed to be 
influenced by multiple genetic and environmental factors. Here, we evaluated 
whether the risk and severity of endometriosis are associated with polymorphisms 
in estradiol-synthesizing enzyme genes: the Ser312Gly polymorphism in 
17-beta-hydroxysteroid dehydrogenase type 1 (HSD17B1) and the Arg264Cys 
polymorphism in cytochrome P450, subfamily XIX (CYP19).
METHODS: All participants underwent diagnostic laparoscopy, and the stage of 
endometriosis was determined according to the Revised American Fertility Society 
classification. Of the 138 women enrolled, 59 had no endometriosis, 21 had stage 
I, 10 had stage II, 23 had stage III and 25 had stage IV. SNPs were 
discriminated by allele-specific oligonucleotide hybridization.
RESULTS: Individuals having at least one A-allele (A/G or A/A genotype) of 
HSD17B1 showed a significantly increased risk of endometriosis (A/G genotype: 
adjusted OR, 3.06; 95%CI 1.21-7.74; A/A genotype: adjusted OR, 3.02; 95%CI 
1.08-8.43). There was a significant trend associating A/G + A/A genotypes with 
severity of endometriosis (P for trend < 0.01). No statistically significant 
association was found for the CYP19 polymorphism.
CONCLUSIONS: Evidence for association between the Ser312Gly polymorphism in 
HSD17B1 and endometriosis was found in a Japanese population. The A-allele of 
HSD17B1 appears to confer higher risk for endometriosis.