Apolipoprotein E polymorphisms and spontaneous pregnancy loss in patients with endometriosis

Endometriosis affects 10 of women during their reproductive years, many of whom report high rates of spontaneous pregnancy loss (SPL). We examined whether gene polymorphisms in apolipoprotein E (APOE), which is involved in lipoprotein metabolism, are associated with endometriosis and/or endometriosis-associated infertility. We conducted a cross-sectional genetic association study of women surgically confirmed to have endometriosis (n 345) and no surgical evidence of the disease (n 266). Genotyping of APOE polymorphism (?2, ?3, ?4) was conducted by polymerase chain reactionrestriction fragment length polymorphism followed by visualization of specific patterns by gel electrophoresis. Statistical significance of differences in genotype and allelic frequencies was assessed using Pearsons (2) test and Risk analysis. Overall, we found no association between APOE genotype and diagnosis of endometriosis. However, patients with endometriosis who reported at least one SPL were three times more likely to be ?2 carriers and 2-fold less likely to be ?4 carriers. Compared with ?3 carriers, patients with endometriosis who were ?2 carriers and had at least one live birth reported four times the rate of SPL, while ?4 carriers were 0.4-fold less likely to report an SPL. Our data suggest that there may be an association between APOE allelic frequency and SPL in patients with endometriosis, which appears to be independent of mechanisms associated with infertility, an intriguing observation that deserves further investigation.