Gene polymorphisms and HLA-G expression in spontaneous abortions

Abstract

IntroductionHLA-G and HLA-E are claimed to play a role in establishing maternal–fetal immune tolerance and in maintaining pregnancy. The presence of polymorphism in the HLA-G gene could cause a deficient or excessive expression of the HLA-G and HLA-E molecules. These anomalies could eventually cause pregnancy losses. Materials and methodsClinical study. A total of 90 patients were included in this study. These patients suffered spontaneous abortions between weeks 6 and 11 of pregnancy. We have analysed the most important polymorphisms of the HLA-G gene through different genetic studies and HLA-G and HLA-E expression through immunostaining in human cytotrophoblast cells from first trimester spontaneous abortions obtained by hystero-embryoscopy. Placental biopsies obtained with this technique have minimal risk of maternal contamination and provide a reliable embryo karyotype. ResultWe found that the expression of HLA-G and HLA-E is similar between samples of normal and abnormal karyotype. In addition, we found no evidence of association between the HLA-G polymorphisms and altered expression in both abortion groups. DiscussionThis is the first study to analyse embryonic tissue which was unable to complete its implantation successfully. We used a new technique with a minimal risk of maternal contamination which provided a reliable karyotype. Our results suggest that, neither HLA-G nor HLA-E protein expression seem responsible for spontaneous pregnancy losses in the first trimester.