母血中胎源性RASSF1A基因的检测及其在子痫前期中的临床意义

目的:初步探讨孕妇血浆中胎源性Ras相关区域家族1A(Ras association domain family 1A,RASSF1A)基因的动力学特点及其在子痫前期中的含量变化。方法:应用2种甲基化敏感的限制性内切酶HinP1I和HhaI去除孕妇血浆中非甲基化的RASSF1A序列,保留超甲基化RASSF1A序列。通过含目的基因的质粒标准品绘制标准曲线,结合荧光定量PCR(FQ-PCR)技术测定血浆中酶切后RASSF1A基因的含量,反映游离胎儿DNA水平。同时检测β-actin基因确保酶对非甲基化序列的完全消化。结果:①最早可在妊娠7+3周检测出孕妇血浆中超甲基化的RASSF1A基因;②孕妇血浆中超甲基化RASSF1A基因的含量随妊娠的进程逐渐增加,且在分娩后24 h内消失;③未妊娠组中均未检测到超甲基化的RASSF1A基因;④妊娠晚期子痫前期组超甲基化RASSF1A基因含量为正常同期妊娠组的3.52倍。结论:孕妇血浆中超甲基化的RASSF1A基因可以作为胎儿表观遗传学标志物,其水平的异常变化或能提示子痫前期-子痫的发生。     

子痫前期孕妇外周血浆中高甲基化SIM2基因的含量变化

目的:通过检测高甲基化SIM2基因来分析游离胎儿DNA在正常妊娠孕妇及子痫前期孕妇外周血浆中含量的变化。方法:共收集114例外周血浆样本(包括健康未妊娠女性志愿者10例,产后48小时健康女性10例,正常妊娠孕妇57例,子痫前期孕妇37例),利用HpaⅡ、MspⅠ分别对提取的血浆DNA进行甲基化酶切反应后再进行实时荧光定量PCR反应,相对定量法检测高甲基化SIM2基因的含量。结果:①10例健康未妊娠女性志愿者及产后48小时健康女性外周血浆中均未检测出高甲基化SIM2基因;②57例正常妊娠孕妇中有43例检测出高甲基化SIM2基因,在不同妊娠阶段高甲基化SIM2基因含量的差异有统计学意义,高甲基化SIM2基因的含量在中期妊娠是早期妊娠的2.33倍,晚期妊娠是早期妊娠的5.28倍;③37例子痫前期孕妇中有36例检出高甲基化SIM2基因,高甲基化SIM2基因的含量在轻度子痫前期孕妇血浆中是正常晚期妊娠的3.05倍,在重度子痫前期孕妇中是正常晚期妊娠的6.32倍。结论:高甲基化SIM2基因是可靠的胎儿特异性标记,在孕妇外周血浆中高甲基化SIM2基因的含量随妊娠进展而增加,与孕周有关。高甲基化SIM2基因在子痫前期孕妇血浆中含量明显增加,能够反应子痫前期疾病的严重程度。     

子痫前期孕妇外周血中游离胎儿DNA含量变化

目的探讨正常妊娠不同孕周及子痫前期孕妇外周血中游离胎儿DNA含量的变化。方法对2009年8月至2010年9月西安交通大学第二附属医院外周血样本90例(包括健康未孕10例,正常妊娠40例,子痫前期40例),应用甲基特异性PCR的原理及荧光定量PCR的方法,相对定量法检测u-maspin基因的含量。结果 (1)10例健康未孕样本未检出u-maspin基因;(2)40例正常妊娠样本有34例检出u-maspin基因,各孕期u-maspin基因检出量差异具有统计学意义(P<0.05),u-maspin基因的含量中孕是早孕的4.43倍,晚孕是早孕的5.13倍;(3)40例子痫前期样本均检出u-maspin基因,u-maspin基因的含量子痫前期轻度是正常晚孕的2.39倍,子痫前期重度是正常晚孕的5.78倍。结论孕妇外周血中游离胎儿DNA的含量随着妊娠进展而增加,能够反映子痫前期患病的严重程度。     

孕妇外周血中ERG基因甲基化状态及定量研究

目的:探讨ERG基因作为孕妇外周血中胎儿特异性标记物的可行性。方法:随机选取健康未妊娠妇女5例、正常妊娠孕妇65例、产后3天妇女20例的外周血样本,以及早期妊娠行人流的绒毛组织样本10例。应用甲基化敏感限制性内切酶PCR(MSRE-PCR)及荧光定量PCR方法检测样本中ERG基因甲基化状态,并进行相对定量分析。结果:(1)健康未妊娠妇女、顺产后3天妇女外周血浆及孕妇血细胞中均未检出甲基化的ERG基因;(2)绒毛组织样本中甲基化的ERG基因检出率100%;(3)正常妊娠孕妇外周血浆中甲基化ERG基因检出率为76.9%,中期、晚期妊娠ERG基因的含量分别是早期妊娠的3.18倍和5.46倍。结论:甲基化的ERG基因是可靠的胎儿特异性标记;正常妊娠孕妇的外周血浆中甲基化的ERG基因的检出量随孕周增加而增加。     

ERG甲基化作为无创产前诊断唐氏综合征标记的可行性研究

目的探讨ERG基因是否可以作为孕早期血浆中检测胎儿DNA的通用标志物。方法随机选择早期妊娠孕妇70例,并以经体检确定为未孕健康妇女70例、分娩过21-三体胎儿的妇女11例和顺产后3 d妇女20例作为对照组。利用甲基化敏感限制性内切酶HpaⅡ、MspⅠ酶切后进行常规PCR的方法,检测血细胞、绒毛和血浆DNA目的基因ERG21-128序列的甲基化模式,并对妊娠组和对照组样本进行统计学分析。结果位于21号染色体上的ERG基因21-128序列在70例孕8、9、10周孕妇绒毛组织中甲基化而在母体血细胞中未甲基化,绒毛甲基化检出率为100%;在血浆中游离胎儿DNA ERG基因21-128序列的甲基化检出率为77.1%,敏感度为77.1%。其中8、9、10周甲基化差异无统计学意义（P〉0.05）。在70例未孕健康妇女、11例生产过21三体胎儿的健康妇女和20例产后3 d妇女的对照组的血浆中ERG 21-128序列均未甲基化。结论在母体和胎儿DNA中,ERG基因21-128区的甲基化有显著性差异,实验方法也比较简单,提示了ERG是无创性产前诊断DS的一个潜在标记物。     

孕妇血浆中胎儿DNA在产前诊断中的应用

目的依据孕妇血浆中存在游离胎儿DNA的理论,寻找一种无创性产前基因诊断的新方法。方法提取42例孕14~40周的产妇血浆中游离胎儿DNA,采用引物延伸预扩增(primerextensionpreamplification,PEP)后行PCR,特异性扩增其Y染色体重复序列(DYZ3)基因。同时采用9个短串联重复序列(shorttandemrepeat,STR)多态性位点的多重扩增方法以检出血浆中胎儿DNA。结果DYZ3-PCR中,32例妊娠男性胎儿孕妇中有28例血浆中出现基因扩增带,检出率为87.5%,10例妊娠女性胎儿孕妇血浆有2例假阳性结果。性别总符合率为85.7%,STR-PCR中,检测出孕妇血浆中父源性胎儿DNA的存在。结论应用孕妇血浆中胎儿DNA作产前诊断敏感性和特异性较高,是一种无创性产前基因诊断方法,具有广泛的临床应用前景。     

孕妇血浆中胎儿DNA在产前诊断中的初步应用--胎儿SRY基因、STR基因型的鉴定

目的 :利用孕妇血浆中游离胎儿 DNA进行非创伤性产前基因诊断。方法 :对 6 5例 5～ 4 1孕周孕妇血浆胎儿DNA进行 SRY的 PCR扩增 ,以检出男性胎儿 DNA;同时采用短串联重复序列 (STR)多态位点即 CSFIPO、TPOX、THO1(CTT)三个位点的复合扩增方法对 19例妊娠女性胎儿的孕妇血浆 DNA进行扩增 ,以检出女性胎儿 DNA。两种扩增均采用母体血浆直接作为模板进行。结果 :SRY- PCR中 ,4 6例妊娠男性胎儿的孕妇中 ,有 30例血浆中出现 SRY基因扩增带 ,19例妊娠女性胎儿的孕妇血浆中仅 1例孕中期者为假阳性 (5 .3% )。本研究孕早、中、晚期的性别符合率分别为 6 0 %、84 .0 9%、5 0 % ,总符合率为 73.85 % .CTT- PCR中 ,19例妊娠女胎孕妇血浆中有 15例检出父源性等位基因即女性胎儿 DNA。结论 :应用孕妇血浆中胎儿 DNA作产前诊断敏感性和特异性较高 ,尤其是在孕中期 ,它是一种非创伤性产前诊断方法 ,适用于临床。     

母血清及血浆中胎儿游离DNA的研究进展

发现母血浆及血清中胎儿游离DNA,为无创性产前诊断技术开辟新途径.利用母血中有男胎睾丸确定基因(SRY)特异性序列确定胎儿DNA存在.用PCR技术扩增SRY的单拷贝序列(DYS14),确定性别敏感性60%～100%.利用实时定量PCR技术测定母血清和血浆中胎儿DNA浓度,妊娠7周母血清中可确定胎儿DNA,随妊娠周增加胎儿DNA量也增高.另证明非整倍体核型胎儿在母血浆中的DNA浓度高于正常核型胎儿,母血浆中定量测定胎儿游离DNA技术可能成为筛查染色体非整倍体核型胎儿的一种手段.     

母血清及血浆中胎儿游离DNA的研究进展

发现母血浆及血清中胎儿游离DNA，为无创性产前诊断技术开辟新途径。利用母血中有男胎睾丸确定基因(SRY)特异性序列确定胎儿DNA存在。用PCR技术扩增SRY的单拷贝序列(DYSl4)，确定性别敏感性60％～100％。利用实时定量PCR技术测定母血清和血浆中胎儿DNA浓度，妊娠7周母血清中可确定胎儿DNA，随妊娠周增加胎儿DNA量也增高。另证明非整倍体核型胎儿在母血浆中的DNA浓度高于正常核型胎儿，母血浆中定量测定胎儿游离DNA技术可能成为筛查染色体非整倍体核型胎儿的一种手段。     

利用母胎间基因甲基化的差异性检测母血中微量胎儿DNA方法的建立

随着表观遗传学方法 在无创性产前诊断中的逐步应用,第一个普通应用的胎儿表观遗传学标记低甲基化maspin基因突破了胎儿性别和基因多态性的局限,为母血中胎儿DNA应用于临床开辟了新的领域,象征着非创伤性产前诊断的研究向前迈进了一大步[1].甲基化特异的聚合酶链反应(polymerase chain reaction,PCR)技术是低甲基化maspin序列检测的重要手段,然而该方法 操作复杂且造成大量DNA降解,给微量胎儿DNA的定量分析带来困难.有研究者发现,RASSF1A基因启动子区在母血细胞中处于低甲基化状态,而在胎盘细胞中处于超甲基化状态[2-3];同时发现母血浆中超甲基化的RASSF1A序列中存在胎儿SNP基因型.     

荧光定量PCR检测孕妇血浆中胎儿DNA的研究

目的探讨荧光定量PCR（fluorescence quantitative PCR，FQ-PCR）方法检测孕妇血浆中胎儿DNA的可行性，探讨胎儿DNA在孕妇血浆中的含量及其在孕期的变化规律。方法以胎儿SRY基因序列作为胎儿DNA在孕妇血浆中的标志，应用荧光MGB（Minor Groove Binder）探针实时定量PCR方法连续测定30例孕妇在不同孕期和产后共237份血浆标本中胎儿DNA的含量。结果使用该方法最低可检测到20000个女性DNA中的一个男性DNA。孕妇血浆中最早检出SRY序列的时间为孕6^＋6周。孕8周起，所有怀男胎孕妇的标本中均可检出SRY序列，其含量随着妊娠的进展而增高，在晚期妊娠达高峰，产后24～48h血浆中SRY序列检测均为阴性。胎儿DNA在孕妇血浆总DNA含量中的相对浓度分别为孕早期4．88％、孕中期6．10％、孕晚期4．77％。全部实验无假阳性和假阴性出现。结论FQ-PCR方法是一种灵敏度和准确性高，特异性强的定量检测孕妇血浆中胎儿游离DNA的方法，孕妇血浆中存在高浓度的胎儿DNA，可用于无创伤性产前基因诊断。     

Quantitative analysis of fetal DNA in maternal plasma in gestational diabetes mellitus,iron deficiency anemia and gestational hypertension pregnancies

Abstract

Objective: To quantify circulating fetal DNA (fDNA) levels in the second and third trimesters of normal healthy pregnant individuals and pregnant women with the following clinical conditions: gestational diabetes mellitus (GDM), iron deficiency anemia and gestational hypertension (GHT).

Methods: The SRY gene located on the Y chromosome was used as a unique fetal marker. The fDNA was extracted from maternal plasma and the SRY gene concentrations were measured by quantitative real-time polymerase chain reaction (PCR) amplification using TaqMan dual labeled probe system.

Results: No significant differences were observed in the mean fDNA concentration between normal and GDM pregnancy samples (p?>?0.05) and also between normal and anemic pregnancy samples (p?>?0.05) in both trimesters, but significant differences were observed between the third trimester normal and GHT pregnancy samples (p?=?0.001). GDM and iron deficiency anemia do not affect the levels of fDNA in maternal plasma while GHT significantly elevates the levels of fDNA in maternal plasma.

Conclusions: Increased amount of circulating fDNA in maternal plasma could be used for early identification of adverse pregnancies. GDM and anemia do not affect the levels of fDNA in maternal plasma while GHT significantly elevates the levels of fDNA in maternal plasma. Hence, the elevated fDNA values could be used as a potential screening marker in pregnancies complicated with GHT but not with GDM and iron deficiency anemia.     

Non-invasive fetal sex determination using real-time PCR.

OBJECTIVE: The aim of this study was to evaluate the specificity and sensitivity of the real-time quantitative PCR method for fetal gender determination in early pregnancy. METHODS: Blood samples were collected from 46 pregnant women prior to amniocentesis. DNA was extracted from maternal plasma using a QIAmp DNA Blood Mini Kit. DNA samples were subjected to real-time quantitative PCR amplification of SRY (as a fetus-specific marker) and beta-globin (as a marker for total plasma DNA) genes. RESULTS: The beta-globin gene sequence was detected in all samples. The SRY gene was detected in 25 of 28 plasma samples from women with male fetuses and in none of the 18 samples from women with female fetuses (sensitivity 89.2% and specificity 100%). The fetal gender was correctly determined in 43 (93.5%) of 46 maternal plasma samples. The concentration of the beta-globin gene ranged from 161 to 25,568 genome-equivalents (GE)/mL (median 1051.1), while the concentration of the SRY gene ranged from 5 to 166 GE/mL (median 27.4). The percentage of free fetal DNA ranged from 0.1% to 46.1% (median 2.0%). CONCLUSION: Amplification of fetal DNA from maternal plasma by real-time quantitative PCR is a promising method for fetal sex determination in early pregnancy. However, further studies are necessary before this procedure can be included into a clinical routine.     

Fetal sex determination from maternal plasma in pregnancies at risk for congenital adrenal hyperplasia

OBJECTIVE: To determine first-trimester fetal sex by isolating free fetal DNA from maternal plasma. METHODS: The index case was a pregnant woman who previously delivered a girl with congenital adrenal hyperplasia. The SRY gene as a marker for the fetal Y chromosome was detected in maternal serum and plasma by quantitative polymerase chain reaction analysis. Simultaneously, we performed the same test in 25 and 19 women in the first and second trimester, respectively, and compared plasma results with fetal gender as assessed by prenatal karyotyping or as seen at ultrasound or birth. RESULTS: In 44 of 45 patients at gestational ages ranging from 8 3/7 to 17 3/7 weeks, we correctly predicted fetal sex using quantitative polymerase chain reaction analysis of the SRY gene in maternal plasma. In one case, the test result was inconclusive. Overall, fetal sex was correctly predicted in 97.8% of cases (95% confidence interval 88.2%, 99.9%). CONCLUSION: Amplification of free fetal DNA in maternal plasma is a valid technique for predicting fetal sex in early pregnancy. In case of pregnancies at risk for congenital adrenal hyperplasia, the technique allows restriction of dexamethasone treatment to female fetuses resulting in a substantial decrease of unnecessary treatment and invasive diagnostic tests.     

First trimester fetal sex determination in maternal serum using real-time PCR

OBJECTIVE: Fetal sex prediction can be achieved using PCR targeted at the SRY gene by analyzing cell-free fetal DNA in maternal serum. Unfortunately, the results reported to date, show lack of sensitivity, especially in the first trimester of pregnancy. Therefore, determination of fetal sex by maternal serum analysis can not replace caryotype analysis following chorionic villus sampling. PATIENTS AND METHODS: A new highly sensitive real-time PCR was developed to detect a SRY gene sequence in maternal serum. Analysis was performed on 121 pregnant women during their first trimester of pregnancy (mean gestational age: 11.8 weeks). Among them, 61 had at least one previous male-bearing pregnancy. Results were compared to fetal sex. RESULTS: SRY PCR analysis of maternal serum was in complete concordance with fetal sex. Among the 121 pregnant women, 61 were bearing a male fetus and 60 a female fetus No false negative results were observed. Furthermore, no false positive results results occurred although 27 women carried female fetus during the current pregnancy, had at least one previous male-bearing pregnancy. DISCUSSION AND CONCLUSION: This study demonstrates that a reliable, non-invasive sex determination can be achieved by PCR analysis of maternal serum during the first trimester of pregnancy. This non-invasive approach for fetal sex prediction should have great implications in the management of pregnant women carriers of an X-linked genetic disorder. Prenatal diagnosis is thus performed for male fetuses only, avoiding invasive procedures and the risk of fetal loss for female fetuses.     

运用O型血孕妇血浆中游离胎儿DNA检测胎儿ABO血型

目的:探讨利用O型血孕妇血浆中游离胎儿DNA检测胎儿ABO血型的可行性。方法:用酚/氯仿法从39例O型血孕妇(孕36~40+3周)且孕男性胎儿的血浆中提取胎儿DNA,巢式PCR扩增血浆中的SRY基因证实胎儿DNA存在,再用特异性序列-聚合酶链反应(SSP-PCR)检测胎儿ABO血型。用常规血清学方法测母体及新生儿血型。结果:10例孕A型血胎儿的孕妇血浆中扩增出A基因8例,6例孕B型血胎儿的孕妇血浆中扩增出B基因6例,23例孕O型血胎儿扩增出O基因而无A或B基因21例,准确性和敏感性分别为89.7%(35/39)和87.5%(14/16)。结论:利用孕妇外周血中游离胎儿DNA检测胎儿ABO血型可行,对诊断和预防新生儿ABO血型不合性溶血病的发生具有积极意义。     

First-trimester fetal sex determination in maternal serum using real-time PCR.

Fetal sex prediction can be achieved using PCR targeted at the SRY gene by analysing cell-free fetal DNA in maternal serum. Unfortunately, the results reported to date show a lack of sensitivity, especially during the first trimester of pregnancy. Therefore, determination of fetal sex by maternal serum analysis could not replace karyotype analysis following chorionic villus sampling. A new highly sensitive real-time PCR was developed to detect an SRY gene sequence in maternal serum. Analysis was performed on 121 pregnant women during the first trimester of pregnancy (mean gestational age: 11.8 weeks). Among them, 51 had at least one previous male-bearing pregnancy. Results were compared with fetal sex. SRY PCR analysis of maternal serum was in complete concordance with fetal sex. Among the 121 pregnant women, 61 were bearing a male fetus and 60 a female fetus. No false-negative results were observed. Furthermore, no false-positive results occurred, even though 27 women carrying a female fetus during the current pregnancy had at least one previous male-bearing pregnancy. This study demonstrates that a reliable, non-invasive sex determination can be achieved by PCR analysis of maternal serum during the first trimester of pregnancy. This non-invasive approach for fetal sex prediction should have great implications in the management of pregnant women who are carriers of an X-linked genetic disorder. Prenatal diagnosis might thus be performed for male fetuses only, avoiding invasive procedures and the risk of the loss of female fetuses.     

Echocardiographic assessment of cardiovascular hemodynamics in normal pregnancy

OBJECTIVE: The factors affecting cardiac output in normal pregnancy remain controversial. This study prospectively evaluates maternal central hemodynamics and cardiac structure and function by echocardiography, together with maternal stature correction and correlation of these variables in healthy pregnant women in the latter half of pregnancy. METHODS: One hundred sixty echocardiographic studies were performed in 35 healthy pregnant women for longitudinal evaluation from early second trimester until term and 6-12 weeks postpartum. RESULTS: Cardiac output increased significantly at the early to mid third trimester and was maintained until term. It increased predominantly in the latter half of pregnancy, and peak cardiac output of 46-51% occurred from a 15% increase in heart rate and 24% increase in stroke volume. Maternal cardiac output measured in the early third trimester showed a good correlation with maternal body surface area (r = 0.72; P <.001) and fetal birth weight (r = 0.52; P =.008). Left ventricular systolic function was preserved until term. CONCLUSION: Maternal cardiac output peaks in the early to mid third trimester and is maintained until term. Significant correlations were observed among maternal cardiac output, maternal body surface area, and fetal birth weight.