Meta-analysis of the human leukocyte antigen-G (HLA-G) 14 bp insertion/deletion polymorphism as a risk factor for preeclampsia.

The non-classical major histocompatibility complex, human leukocyte antigen (HLA)-G, plays an important role in pregnancy. HLA-G mediates proper interaction between maternal immune cells and fetal trophoblasts invading the uterine wall, to ensure successful placental development and function. Several HLA-G gene variants have been shown to be associated with development of preeclampsia (PE), but the reported associations of the HLA-G 14 base pair (bp) insertion/deletion (I/D) polymorphism (rs66554220) with PE are inconsistent. In this meta-analysis of HLA-G 14 bp I/D in each member of the family triad, we estimated risk (odds ratio [OR], 95% confidence interval) of associations with PE based on nine published offspring, nine mother and three father case-control studies. No significant increased risk associations between PE and HLA-G 14 bp I/D were detected in any of the family triad members (offspring: OR = 1.08-1.21, P = 0.57-0.74; mothers: OR = 1.11-1.28, P = 0.07-0.44; fathers: OR = 1.09-1.65, P = 0.07-0.70). Of the 20 comparisons performed, 14 (70%) were non-heterogeneous and seven of these had zero heterogeneity (I(2) = 0%). Sensitivity treatment confirmed robustness for the overall lack of association for HLA-G 14 bp I/D. In subgroup analysis, significant association between HLA-G 14 bp I/D and PE was shown in offspring from primipara (OR = 1.66-1.95, P = 0.04) and European Caucasian pregnancies (OR = 1.37-2.03, P = 0.02-0.03). However, heterogeneity and sensitivity tests suggest that further investigation is needed to determine if HLA-G 14 bp I/D is involved in trophoblast HLA-G expression and PE development in these subgroups.