Research On The HLA-G 14bp Gene Polymorphism In The Pathogenesis Of Early (Late) Onset Severe Pre-eclampsia

Pre-eclampsia (PE) is a pregnancy-associated disorder, especially severe PE is a leading cause of morbidity and mortality among mothers and infants worldwide.In the 1980s, American scholar noticed that severe PE occurred in second trimester of pregnancy have fatal danger to maternal, and is associated with adverse neonatal outcomes.Put forward early onset severe PE (early onset severe pre-eclampsia, EOSP). At present, for early onset severe PE not unified limited scope, some scholars think PE onsets before 32 weeks's gestationa as early, more scholars consider premature survial in gestational age reached 34 weeks's to get improved obviously, so think of Early onset severe PE is that onsets before 34 weeks gestation while late onset severe PE onseting after 34 weeks ggestation.At present the pathogenesy of PE be consider as poor placentation caused by reduced trophoblast invasion and maladaptation of uteroplacental arteries, Placental "shallow implantation", is initiating factors of the pathogenesis of PE, but severe PE why present two performance of early and late onset? is it Pathogenesis consistent? no clear.More and more research shows that early oneset severe PE mainly through the placenta lesions may affect the maternal-fetal, whereas late onset PE-like symptoms have a direct impact on the mothers.Pregnancy is considered half allogeneic transplant,early pregnancy,extravillous cytotrophoblasts of fetal origin invade the uterine spiral arteries of the decidua and myometrium.Though extravillous cytotrophoblasts directly facing the maternal cells,although is half the same antigen,but not by maternal immune cells recognition, was considered trophoblastic itself factors and maternal microenvironment through molecular and cellular immune tolerance between unique formation,which may cause abnormal immune tolerance pathological pregnancy such as preeclampsia happen.Thus speculate that the pregnancy is a special kind of physiological condition,no matter the normal or abnormal,all is maternal-fetal both the result of joint action.And genetic immune related important genes HLA antigen, humanleukocyte (HLA) gene location in the short arm of 6 chromosome, The non-classical MHC class lb member, HLA-G, is assigned an essential role in pregnancy. HLA-G is mainly expressed by extravillous trophoblasts (EVTs) in decidual tissue, and inhibits maternal uterine natural killer (NK) cells from killing trophoblasts.This interaction is essential for the feto-maternal immune balance needed for optimal trophoblast invasion during placentation. Study found HLA-G gene has limited polymorphism, think its polymorphism existence may cause the placenta HLA-G molecular expression amount of different, and leading pathologic pregnancy,the presence of a 14 bp insertion/deletion (+14bp/-14bp) in the 3'untranslated region (UTR) of HLA-G is very unique, become research focus of HLA-G polymorphism and PE,but mostly relationship research conclusion is differ even contradictory. In-depth analysis we found that most research did not put severe PE divided into early and late onset to analyze, but as a class to statistical, this might confuse HLA-G 14bp polymorphism with different effects of early and late onset sewere PE.ObjectiveThrough the study of the different distribution of HLA-G 14bp polymorphism on early and late PE,discuss different influence of HLA-G 14bp polymorphism on susceptibility of early and late PE.Materials and methods1 MaterialsCollect 83 patients of severe PE between October 2008 and March 2010 in the Third Affiliated Hospital of Zhengzhou University Hospital,according to the seventh edition of obstetrics and gynecology of People's medical publishing house as diagnostic criteria,And with reference to the ACOG standard. And the exclusion of chronic hypertension,cancer,endocrine disease,diabetes,kidney disease,inflammation etc. And all patients were followed up to 12 weeks postpartum. acording to the different gestational age of pathogenesis into early onset group 48 cases (<34 weeks) and late onset group 35 cases (≥34 weeks). Randomly a normal pregnancy group 40 cases(≥37weeks), were due to social factors to caesarean section.The pregnant women of the three groups were all residents of Henan Province, Han nationality, and no history of mixed marriages, non-blood relations. Through comparing the maternal age and pregnancy and childbirth frequency, there was no significant difference (P>0.05).2 methodsBy PCR method, PCR amplification products of the electrophoresis by 8% the degeneration polyacrylamide gel.According to the different 14bp polymorphism, HLA-G gene Exon8 PCR amplification products in electrophoresis have three types, namely:amplification products of a belt, a length of 210bp,can be interpreted as homozygous deletion (-14bp/-14bp); amplified products as two belts, respectively, the length of 210bp and 224bp,can be interpreted as heterozygotes (-14bp/+14bp); Amplified products as a belt, a length of 224bp,can be interpreted as the homozygous insertion(-14bp/+14bp).and respectively choose deletion homozygote(-14bp/-14bp)and insertion homozygous (+14bp/+14bp) of the PCR reaction stock solution,purified and sequenced.Then,results and GenBank Blast sequence be compared with the HLA-G Exon8 fragment match.3 Statistical analysisUsing the statistical analysis software SPSS 16.0 system, Counting material byχ2-test, measuring material using t-test. Goodness of fitχ2-test be applied to determine whether the genotype distribution of Hardy-Weinberg equilibrium. Use direct calculation method calculate respectively the alleles frequency,the genotype frequency of mother and child and the frequency of genotype compatibility in mother-child among the three groups.χ2-test conditions that do not fit the data with the Fisher exact probability method to calculate P values. As a=0.05 for inspection standard.Results1 Comparison of clinical general informationThe age of pregnant women in three groups were not significant difference (P >0.05),but gestational age and birth weight in early and late onset severe PE were lower than normal pregnancies group,and the gestational age and birth weight in early onset group were lower than late onset group (P<0.05)2 HLA-G gene 14bp polymorphismThe genotype frequency of HLA-G gene 14bp polymorphism distribution in mother and newborn of three groups are all accord with Hardy-Weinberg equilibrium (P>0.05) spectively. The gene of the three groups accord with genetic equilibrium.3.1 HLA-G 14bp polymorphism allele and genotype frequency comparison in three groups of pregnant women (1) The allele comparison of the pregnant women in the three groups:Early onset severe PE group+14bp was 24.0%,-14bp was 76%;while the late onset group were 34.3% and 65.7%;while the gourp of Normal pregnancies were 28.8% and 71.2%. The difference of three groups were not statistically significant(P>0.05).(2) The genotype comparison of the pregnant women in the three groups:Early onset severe PE group(-14bp/-14bp), (-14bp/+14bp), (+14bp/+14bp) genotype frequencies respectively was 58.3%,35.4%,6.3%, while the late onset group, the frequency were 40.0%,51.4%,8.6%, and the normal pregnant group,the frequency were 45.0%,52.5%,2.5%, compared the genotype frequency distribution, the differences were not statistically significant (P>0.05).3.2 HLA-G 14bp polymorphism allele and genotype frequency comparison in three groups of newborns(1) The allele comparison of the newborns in the three groups:early onset severe PE group of 14bp polymorphism allele frequency was +14bp 42.7%,-14bp 57.3%; late onset severe PE was +14bp35.7%,-14bp 64.3%, normal group was+14 bp 26.2%,-14bp73.8%.(2) The genotype comparison in three newborns:early onset severe PE group (-14bp/-14bp), (-14bp/+14 bp), (+14 bp/+14 bp) genotype frequencies were 27.0%,60.4%,12.6%;while late onset severe PE group were 42.8%,42.8%,14.3%;the normal pregnant group were 52.5%,42.5%,5.0%. Newborns with normal group of 14bp deletion polymorphism allele frequency and (-14bp/-14bp) genotype frequency was significantly higher than the early onset group (P<0.05). the differences were not statistically significant in early onset group and late onset group(P>0.05).3.3 HLA-G 14bp polymorphhism genotype Compatibility of meternal-fetus frequency comparison in three groups. The frequency distribution of maternal(-14bp/-14bp)/fetus(+14bp/-14bp) genotype binding in the early onset group was significantly higher than late onset group and the normal groups (P<0.05), The frequency distribution of maternal (+14bp/-14bp)/fetus(-14bp/-14bp) genotype binding in the early onset group was significantly lower than normal group (P<0.05).the differences were not statistically significant in early onset group and late onset group(P>0.05).Conclusion1. The different genotypes compatibility in materal-fetus of HLA-G14bp polymorphism may relate the predisposition of early onset severe PE, such as maternal(-14bp/-14bp)/fetus(-14bp/+14bp); some genotypes compatibility may relate the resistance of early onset severe preeclampsia, such as maternal(+14bp/-14bp)/fetus(-14bp/-14bp).2. The 14bp deletion polymorphism of neonates may reduce the occurrence of early onset severe PE.