Dopamine receptor D2 genotype (3438) is associated with moderate/severe endometriosis in infertile women in Brazil

ObjectiveTo compare the prevalence of dopamine receptor D2 polymorphisms in patients with peritoneal endometriosis and in healthy control subjects.DesignCase-control study.SettingUniversity hospital.Patient(s)One hundred seven women aged ≥18 years who were enrolled when seeking care for infertility caused by peritoneal endometriosis or for tubal ligation.Intervention(s)We performed DNA extraction of peripheral blood, followed by polymerase chain reaction to confirm single-strand polymorphisms and to sequence two polymorphisms.Main Outcome Measure(s)We sequenced two polymorphisms in exon 7 of the dopamine receptor D2 (DRD2) gene. Polymorphism 1 occurs in nucleotide 3420 (cytosine to thymine, 313 histidine), and polymorphism 2 occurs in nucleotide 3438 (cytosine to thymine, 319 proline).Result(s)The frequency of the DRD2 polymorphism 2 was increased in subjects with peritoneal moderate/severe endometriosis. Analysis of the DRD2 genotypes demonstrates an odds ratio of 2.98 (95% confidence interval 1.47–6.04) for polymorphism 2 in peritoneal moderate/severe endometriosis.Conclusion(s)Our results revealed that an excess of DRD2 polymorphism 2 was found in exon 7 in women with peritoneal moderate/severe endometriosis. The presence of polymorphism 2 could cause a defect in a post-receptor signaling mechanism, resulting in a mild increase in serum prolactin levels. Thus, the potential angiogenic role of prolactin may play a role in the implantation of ectopic endometriosis tissue.