MICROSOMAL EPOXIDE HYDROLASE POLYMORPHISM AND RISK OF SPONTANEOUS-ABORTION

We conducted a nested case control study to examine the association of microsomal epoxide hydrolase polymorphism with spontaneous abortion. The analysis included 127 cases and 107 controls from a rural communit y in China. The prevalence of the homozygous wild-type (AA), the heter ozygous variant (Aa), and the homozygous variant (aa) in exon 3 of epo xide hydrolase was 13.4%, 34.6%, and 52.0% in cases and 27.1%, 30.8%, and 42.1% in controls, respectively. In contrast, the variant genotype s in exon 4 of epoxide hydrolase were less frequent in cases than cont rols. Using women with genotype AA as the referent, the adjusted odds ratio of spontaneous abortion was 2.69 [95% confidence interval (CI) = 1.33-5.42] for those with genotype Aa or aa in exon 3; but it was 0.4 5 (95% CI = 0.22-0.94) for those with genotype Aa or aa in exon 4, ind icating that the two variants have opposite associations with spontane ous abortion. The findings persisted after adjustment for age, educati on, parity, smoking, alcohol use, occupation, and pesticide exposure, as well as in subgroup analysis. Moreover, for the variant genotypes A a or aa in exon 3, the odds ratio was twice as great in those cases wi th three or more spontaneous abortions than in those with fewer sponta neous abortions.