Investigation Of The Relationship Between Down’s Syndrome Serological Prenatal Screening And Gene Polymorphism Of ApoE And MTHFRC677T

Objective: Down’s syndrome is one of the most common chromosomalinherited diseases and this disease can cause obvious tissue and organmalformations, mental retardation and hypoevolutism. Coming along with thebirth of DS children is great pressure to both families and the whole society.To some extent, Down’s syndrome prenatal screening plays an important rolein cutting down birth rate of DS children, raising the diathesis of the nationand keeping the stablelization and development of the society. The combineddetection of serum markers, such as AFP, β-hCG and uE3, for Down’ssyndrome screening is a non-invasive and convenient operation, and it issuitable to be applied in large-scale. The detection of ApoE andMTHFRC677T gene polymorphisms had been used in the studies of AD andother diseases. There was several researches show that ApoE andMTHFRC677T gene polymorphisms might be associated with Down’ssyndrome. In this study, the ApoE and MTHFRC677T gene polymorphisms ofpregnant women with high DS risk and with low DS risk were detected toexplore the relationship between the risk of Down’s syndrome prenatalscreening and gene polymorphism. It was expected to find new theoreticalbasis of aristogenesis through investigating DS prenatal screening inmolecular level.Method: All of the pregnant women were selected from the clients to dothe Down’s syndrome prenatal screening in our hospital. According to theresults of Down’s syndrome prenatal screening,87pregnant women with highDS risk were selected as high-risk group and100pregnant women with lowDS risk were selected as low-risk group.100healthy nonpregnant womenwere selected as controls.5ml venous blood of each object was taken. White blood cells were separated to extract genome DNA. Polymerase chainreaction-restricted fragment length polymorphism (PCR-RFLP) was exploredto detect MTHFR C677T gene polymorphisms, and Multiplex amplificationrefractory mutation system (multi-MARS) was used for identifying the ApoEgene polymorphisms. Finally the genotypes detected by PCR-RFLP andmulti-MARS were evidenced by sequencing. Meanwhile, serum was separatedto detect the concentration of serum markers. The serum concentrations ofAFP, β-hCG and uE3were detected by chemoluminescence immunoassayusing the Access2immunity analytical system (Beckman coulter). Generalclinical data (age, weight and gestational age) of all pregnant women werecollected. Different genotypes and alleles of ApoE and MTHFRC677T genewere counted. The concentrations of AFP, β-hCG and uE3and general clinicaldata in different groups were compared by wilcoxon rank test, and logisticanalysis was used to evaluate the risk of different factors to Down’s syndromehigh-risk.Result:1The concentrations of serum markers in high-risk group (AFP,21.0±7.6μg/L; β-hCG,62.7±9.9μg/L; uE3,0.8±0.2ng/ml) and low-riskgroup (AFP,29.8±8.4μg/L; β-hCG,8.8±3.7μg/L; uE3,1.6±0.5ng/ml) werehigher than that in controls (AFP,5.4±1.3μg/L; β-hCG,1.2±0.4μg/L; uE3,0.06±0.04ng/ml; P<0.01). The concentrations of AFP, β-hCG and uE3, age,weight and gestation age were compared between high-risk and low-riskgroups. Comparing with in low-risk group, pregnant women in high-riskgroup showed lower serum level of AFP as well as uE3, higher level ofβ-hCG, and higher age (high risk group,30±5years; low risk group,26±3years, P<0.01). There was no statistical difference of weight andgestation age in both groups (P>0.05).2The effects of concentrations ofAFP, β-hCG, uE3and age on high DS risk were explored through logisticanlysis. The result showed that the age being greater than or equal to30,β-hCG rising, AFP reduction and uE3decrease were risk factors of highDS risk, and the OR values were21.168,179.660,5.337and7.053.3Threedifferent MTHFRC677T genotypes and two alleles were detected. CC gene frequencies in high-risk group, low risk group and controls were0.36,0.38and0.39. CT gene frequencies in high-risk group, low risk groupand controls were0.36,0.36and0.35. TT gene frequencies in high-risk group,low risk group and controls were0.28,0.26and0.26. C allele frequencies inhigh-risk group, low risk group and controls were0.53,0.56and0.57. T allelefrequencies in high-risk group, low risk group and controls were0.47,0.44and0.43. The genotype frequencies did not significantly deviate from whatexpected by Hardy-Weinberg equilibrium (P>0.05).4Four ApoE genotypesand three alleles were detected. ApoE3/3gene frequencies in high-risk group,low risk group and controls were0.75,0.76and0.75. ApoE4/3genefrequencies in high-risk group, low risk group and controls were0.15,0.13and0.14. ApoE2/4gene frequencies in high-risk group, low risk group andcontrols were0.00,0.01and0.01. ApoE2/3gene frequencies in high-riskgroup, low-risk group and controls were all0.1. ApoE ε2allele frequencies inhigh-risk group, low-risk group and controls were0.052,0.055and0.055.ApoE ε3allele frequencies in high-risk group, low risk group and controlswere0.870,0.875and0.870. ApoE ε4allele frequencies in high-risk group,low-risk group and controls were0.078,0.070and0.075. The genotypefrequencies did not significantly deviate from what expected byHardy-Weinberg equilibrium (P>0.05) as well.5Logistic analysis was used toexplore the interaction between genotypes, age and serum markers. The resultsof logistic analysis showed the interaction between ApoE ε3, MTHFRC677TT allele and β-hCG rising, uE3decrease and the age being greater than orequal to30were risk factors of Down’s syndrome high-risk (P<0.05). The ORvalue was9.327,2.085and4.034.Conclusion:1The age being greater than or equal to30, β-hCG rising,AFP reduction and uE3decreasing were risk factors of high DS risk, and therisk of β-hCG rising was the highest.2ApoE ε3and MTHFRC677T T allele with β-hCG rise, uE3decrease and the age being greater than or equal to30were risk factors of Down’s syndrome high-risk.