利用短串联重复序列产前基因诊断唐氏综合征

目的探索用STR-PCR方法进行唐氏综合征产前基因诊断的可行性。方法收集经羊水细胞培养、核型分析已确诊为唐氏综合征的孕妇羊水标本,提取其中的胎儿DNA,并利用聚合酶链反应扩增21号染色体上4个STR位点（D21S11、D21S1411、D21S2039、D21S2055）,根据扩增产物聚丙烯酰胺凝胶电泳分型结果诊断唐氏综合征患者。结果与核型分析结果对比。结果运用STR-PCR电泳分型技术对10例唐氏综合征孕妇的羊水进行诊断,结果与染色体核型分析一致。结论联用4个位点对唐氏综合征标准型患者进行诊断结果准确度高,适宜产前诊断临床应用。     

应用STR-荧光定量PCR行产前唐氏综合征诊断的初步研究

目的建立快速高效的产前诊断唐氏综合征的方法。方法选取21号染色体上唐氏综合征关键区域内的4个串联重复序列（STR）（D21S1413,D21S1414,D21S1446,D21S1437）作为遗传标记,采用荧光定量PCR扩增技术（QF—PCR）及片段分析技术来检测178例羊水标本,并与羊水标本的染色体核型分析结果相比对,评价QF—PCR方法的特异性和灵敏度。结果所有178例羊水标本中经核型分析证实有19例为21三体,另有2例为性染色体数目异常,19例唐氏综合征样本均可由QF—PCR法扩增检出。19例唐氏综合症样本,采用4对STR引物同时检测,阳性诊断率达100％。结论基于STR的QF—PCR技术具有简单、快速及准确等优点,对唐氏综合征大规模的产前基因诊断具有很好的临床价值。     

PCR-短串联重复法快速产前筛查唐氏综合征的应用价值

目的 探讨PCR短串联重复(PCR-short tandem repeat,PCR-STR)法快速产前筛查唐氏综合征(Down syndrome,DS)的应用价值及7个STR位点多态性分布特点.方法 选择21号染色体核心区域(21q22.1-21q22.2)及其附近的7个STR位点(D21S11、D21S1411、D21S1412、D21S1413、D21S1414、D21S1432、D21S2039),应用PCR-STR扩增对978例高危孕妇羊水样本和82例疑似DS患者外周血样本进行基因诊断筛查检测,并与细胞培养染色体核型分析结果比较.结果 (1)978例羊水和82例外周血样本PCR-STR检测全部成功,7个STR位点多态信息联合分析,以检出2个位点面积比或强度为1∶1∶1三条带;或1个位点1∶1∶1三条带,同时有2个位点面积比或强度为1∶2或2∶1两条带为DS基因诊断标准,共检出DS阳性40例,其中羊水14例阳性,外周血26例阳性.(2)羊水细胞培养染色体核型分析成功961例(98.3％),17例培养失败(1.7％),检出异常染色体核型44例(4.6％),其中14例为DS核型,包括12例标准DS核型,1例易位DS核型,1例嵌合DS核型.17例培养失败羊水经脐带血染色体分析证实均为正常核型.(3)82例可疑DS患者外周血培养全部成功,检出异常染色体核型30例(36.6％),其中26例为DS核型,包括22例标准DS核型,4例易位DS核型;其它异常核型4例.(4)PCR-STR法对7个STR位点联合分析,单例样本可检出1～4个位点为1∶1∶1三条带,或可见2～4个位点为面积比率或强度比为2∶1或1∶2的两条带.羊水和外周血样本DS基因诊断结果与细胞培养染色体核型分析诊断结果完全一致,PCR-STR法快速产前基因诊断DS筛查的灵敏度为100％,未发现假阳性和假阴性结果.(5)7个STR位点杂合率在0.624～0.812,D21S2039和D21S1412位点杂合度最高(＞0.80),D21S1411和D21S1432位点杂合度较低(＜0.70).D21S11和D21S2039位点检出1∶1∶1三条带比率最高(≥40％),而D21S1411、D21S1432、D21S1413位点检出单一条带(纯合率)比率最高(≥30％).结论 PCR-STR法是产前诊断DS的一种快速、有效的筛查方法,7个STR位点联合分析,提供的诊断信息量大,结果准确、可靠.     

用荧光原位杂交技术产前诊断唐氏综合征

目的 用荧光原位杂交技术（Fluorescence in situ hybridization,FISH)快速产前诊断唐氏综合征。方法 采集23名孕妇14～24周的羊水标本，应用荧光标记的针对21号染色体特殊位点的探针（locus-sperifie probe,LSI）及X/Y染色体着丝粒探针（centromeric probe,CEP）对未培养的羊水间期细胞进行FISH；同步进行羊水细胞培养，行常规细胞遗传学染色体核型分析，以核型分析为标准，对FISH技术进行评价。结果 23份标本发生母血污染2例，培养失败1例，将其余20份羊水标本的FISH杂交结果与其染色体核型分析结果进行了比较。FISH分析羊水间期细胞性染色体数目正常者19例（XX11例，XY8例）与羊水中期细胞染色体核型分析结果一致，有1例羊水间期细胞FISH结果为X/XY，染色体核型分析结果为46，XY，因此，FISH与染色体核型分析结果的符合率为95%（19/20）；LSI21探针的FISH结果中21号染色体数目异常者1例，核型分析为典型的21三体，取脐血行G显带染色体核型分析得以验证为47，XY， 21。产前诊断染色体正常者追踪至分娩，新生儿行外周血染色体检查结果皆为正常核型。结论 荧光原位杂交技术可用于羊水间期细胞快速产前诊断唐氏综合征。     

唐氏综合征妊娠再发风险的临床观察

目的通过65例唐氏综合征妊娠史的孕妇羊水细胞核型分析,观察唐氏综合征的再发风险与年龄、夫妇外周血染色体核型、感染因素等的相关性.方法65例唐氏综合征妊娠史的夫妇行外周血染色体核型分析,并于孕15～21w行羊膜腔穿刺术、羊水细胞培养及染色体核型分析.结果发现21三体核型4例,异常率为6.15%(4/65),其中完全型3例,均为高龄孕妇所妊娠,易位型1例.结论夫妇外周血染色体核型正常的低龄孕妇不增加唐氏综合征再发风险;年龄越大,唐氏综合征再发风险越高,高龄孕妇是产前诊断的指征;感染因素可能是导致唐氏综合征妊娠原因之一.     

应用短串联重复序列快速诊断唐氏综合征

目的在实时荧光定量PCR技术的基础上建立一种诊断效果较好、简便、经济的快速诊断唐氏综合征的技术。方法以D21s1411,D21s1259为检测位点,D19s222为参照位点,用SYBR GreenI作为荧光染料,采用荧光定量PCR技术检测37例唐氏综合征及13l例非唐氏综合征胎儿羊水标本的STR片段,分析唐氏综合征组及非唐氏综合征组的4对△Ct值。结果1．非唐氏征组的△Ct1411。及△Ct1259的均数、标准差及95％置信区间均为正值,唐氏征组的△Ct1411及△Ct1259的均数及95％置信区间均为负值;两组间95％置信区间互不重叠。2．非唐氏征组与唐氏征组位点D21s141l及D21s1259△Ct值差异均有统计学意义,分别为t=12．088,P=0．000及t=13．884,P=0．000.3．用D21s1411进行诊断时,ROC曲线下的面积为0．9291,将△Ct1411 0．1327为截止值时的灵敏度与特异度之和最大;用D21s1259进行诊断时,ROC曲线下的面积为0．985,将△Ct1259=-0．2016作为截止值时的灵敏度与特异度之和最大。结论1．以D21s141l和D21s1259为检测位点,应用荧光定量PCR方法检测羊水标本的STR片段,可有效判断胎儿是否为唐氏综合征,检出率达91％以上。2．用SYBR GreenI作为染料进行荧光定量PCR检测,操作步骤简单,成本较低,效果良好。     

唐氏综合征筛查高风险孕妇的羊水产前诊断300例分析

本文分析300例经孕中期筛查为唐氏综合征高风险,并知情选择自愿进行羊水细胞染色体分析的病例。全部患者取羊水细胞培养,染色体分析。共检出胎儿染色体核型异常13例,其中21三体4例,18三体2例,XXY1例,平衡易位及倒位6例。通过本文分析,我们认为要防止或减少唐氏综合征及其他染色体异常患儿出生,羊水细胞培养染色体分析是重要的产前诊断方法。     

NIPT产前基因检测技术在高龄孕妇中临床应用

目的探讨NIPT产前基因检测技术在高龄孕妇中临床应用价值。方法回顾性分析2015年2月到2016年1月在嘉兴市妇幼保健院就诊的高龄妊娠孕妇,通过母体外周血中检测胎儿游离DNA,应用NIPT产前基因检测技术得出胎儿患染色体非整倍性疾病(21-三体综合征、18-三体综合征、13-三体综合征)的风险率。并对高风险胎儿采取羊水或脐血,再行细胞培养染色体核型分析以确定胎儿染色体核型,对所有检测孕妇胎儿均随访至出生后。结果实施无创产前基因检测2250例,结果显示为高风险共13例,其中21-三体综合征高风险为8例,18-三体综合征高风险为3例,l3-三体综合征为2例。以羊水或脐血染色体核型分析的结果为金标准进行结果对照,检测出的8例21-三体综合征高风险中6例确诊为21-三体综合征,1例羊水核型正常,1例羊水46,XN,21cenh+mat;检测出的3例18-三体综合征高风险经核型分析确诊为18-三体综合征1例,2例羊水染色体核型正常;检测出的2例13-三体综合征高风险经核型分析确诊为13-三体综合征1例,1例羊水染色体核型正常;所有检测孕妇胎儿出生后的随访中没有发现假阴性。经统计分析胎儿无创产前基因检测21-三体综合征的准确性为87.5%。18-三体综合征的准确性均为33.33%和13-三体综合征的的准确性均为50%。结论无创产前胎儿非整倍体基因检测可提高产前诊断效率,具有非常高的敏感性和准确性,同时因其无创性有效避免侵入性诊断给孕妇带来流产及感染风险,减轻孕妇的心理负担,避免了唐氏儿的出生,更易被孕妇及家庭所接受,是高龄孕妇意愿选择检测方法的首选。     

家族性SRY基因174T＞G突变一家2例分析

目的 检测21-三体胎儿及其父亲的SRY基因突变情况.方法 采用定量荧光PCR(quantitative fluorescent PCR,QF- PCR)及核型分析方法检测唐氏筛查高风险胎儿羊水标本及其父亲外周血标本.采用- SRY基因PCR产物直接DNA测序检测胎儿及父亲的SRY基因序列.结果 QF - PCR检测胎儿为21-三体,父亲染色体数目未见异常;核型分析结果,胎儿:47,XY,+21,父亲:46,XY;基因测序显示胎儿和父亲均为SRY基因174T＞G突变,此突变导致SRY蛋白的第58个氨基酸由天门冬氨酸(D)变为谷氨酸(E),即D58E.结论 检测到的SRY基因174T＞G突变是一种家族性突变.     

13600例孕中期孕妇唐氏综合征三联筛查结果分析

目的探讨孕妇孕中期血清三联产前筛查与胎儿唐氏综合征检出的关系。方法采用化学发光免疫技术定量检测孕中期(15-20周)孕妇血清中的三项指标(AFP、T-βHCG、uE3),再通过专用软件计算唐氏的风险度,大于1:380定为筛查阳性,建议进一步进行羊水染色体核型分析。结果筛查13600例孕妇有1281例筛查呈阳性,在自愿接受羊水检查的孕妇中,检出唐氏胎儿6例,此外还检出18-三体综合征4例,其他异常染色体胎儿6例。结论孕中期血清三联产前筛查作为对胎儿先天缺陷,尤其是胎儿染色体三体的筛查是行之有效的。筛查结果呈高危孕妇须进一步进行羊水染色体核型分析,以减少缺陷儿的出生。     

Rapid prenatal diagnosis of Down Syndrome using quantitative fluorescent PCR in uncultured amniocytes

Rapid prenatal diagnosis of common chromosome aneuploidies have been successful through quantitative fluorescent PCR (QF-PCR) assays and small tandem repeat (STR) markers. The purpose of our study was to investigate the clinical feasibility for rapid prenatal detection of Down syndrome using the quantitative fluorescent PCR in uncultured amniocytes. DNA was extracted from uncultured amniotic fluid of normal karyotype (n=200) and of Down syndrome (n=21). It was amplified using QF-PCR with four STR markers located on chromosome 21. Among normal samples, the ranges of diallelic peaks for at least one STR marker were 1.0-1.3 for D21S11, 1.0-1.4 for D21S1411 and 1.0-1.5 for D21S1270. Down syndrome samples showed trisomic triallelic patterns or trisomic diallelic patterns. The sensitivity, specificity, and efficiency of the assay for detecting Down syndrome were 95.4%, 100%, and 99.5%, respectively. Rapid prenatal diagnosis of Down syndrome using QF-PCR is a reliable technique that aids clinical management of pregnancy.     

Rapid prenatal diagnosis of trisomy 21 by real-time quantitative polymerase chain reaction with amplification of small tandem repeats and S100B in chromosome 21

Trisomy 21 (Down syndrome) is the most common congenital anomaly, and it occurs in one out of 700-1000 births. Current techniques such as amniocentesis and chorionic villi sampling (CVS) require lengthy laboratory culture procedures and high costs. This study was undertaken to establish a rapid prenatal diagnosis of trisomy 21 using real-time quantitative polymerase chain reaction (PCR) of fetal DNA from amniotic fluid. Real-time quantitative PCR was performed with DNA templates obtained from 14 normal blood samples, 10 normal amniotic fluid samples, 14 Down syndrome blood samples, and 7 Down syndrome amniotic fluid samples. Primers for D21S167 and S100B of chromosome 21 were used. Primers that direct the amplification of the 165-bp fragment of the insulin-like growth factor (IGF)-1 gene on chromosome 12 using a PCR primer were included to generate an internal standard for quantitation. The relative levels of D21S167 and S100B were 2.6 and 2.4 times higher in the blood of Down syndrome patients than those in the control group. The differences between these two groups were statistically significant (p-values were 0.0012 and 0.0016, respectively). The relative levels of D21S167 and S100B were 2.1 and 2.7 times higher in the amniotic fluid of Down syndrome fetuses than those in the control group. The difference between these two groups was statistically significant (p-values were 0.0379 and 0.0379, respectively). Prenatal diagnosis of trisomy 21 by real-time quantitative PCR using STR (small tandem repeats) amplification of D21S167 and S100B is a useful, accurate and rapid diagnostic method. Furthermore, it may also be useful for prenatal diagnosis with fetal DNA from maternal blood, and for preimplantation genetic diagnosis and prenatal counseling.     

Down syndrome with pure partial trisomy 21q22 due to a paternal insertion (4;21) uncovered by uncultured amniotic fluid interphase FISH

OBJECTIVE: To emphasize the usefulness and reliability of fluorescence in situ hybridization (FISH) on uncultured amniotic fluid cells in the prenatal diagnosis of common chromosomal aneuploidies. METHODS: FISH analyses utilizing centromeric, locus-specific or whole chromosome paint DNA probes specific for chromosomes X, Y, 13, 18, 21, and 4 were performed on uncultured amniotic fluid cells or the peripheral blood specimen from the father. Routine chromosome analysis was carried out as well. RESULTS: A prenatal case with partial trisomy 21 due to a paternal cryptic insertion (4;21) was ascertained by a rapid overnight FISH on uncultured amniotic fluid cells. The fetus was delivered at term and had classical features of Down syndrome. CONCLUSION: Our results stress the importance of FISH on uncultured amniotic fluid cells to supplement routine cytogenetics, especially in cases with abnormal ultrasound findings.     

Human chromosome 21-specific DNA markers are useful in prenatal detection of Down syndrome

Trisomy 21 is the most common chromosomal aberration in live births. In this study we employed human chromosome 21-specific short tandem repeat (STR) DNA markers to determine the numbers of chromosome 21 present in fetal cells. Forty amniotic fluid samples from pregnancies complicated with fetal Down syndrome and 98 samples from euploid pregnancies were analyzed for D21S11 and interferon-alpha receptor (IFNAR) gene intervening sequence. Fluorescent dye-labeled primers were used in PCR amplification of these 2 markers. The PCR amplicon was analyzed with an automatic DNA sequence analyzer. The results showed that 35 of 40 fetal Down syndrome samples analyzed for IFNAR showed 3 distinct peaks, while 24 of 30 cases analyzed for D21S11 showed 3 distinct peaks. Two Down syndrome samples showed two uneven peaks. By analyzing 98 euploid pregnancies as controls, the ratios of area under the peaks were determined to be 1.31 +/- 0.22 and 1.96 +/- 0.18 (mean +/- SD) for the euploid pregnancies and pregnancies complicated by fetal Down syndrome with 2 peaks, respectively. Our data showed that altogether 39 of 40 (97.5%) Down syndrome cases were correctly identified based on either the 3-peak pattern in one or more of the DNA markers or the relative peak area ratio calculation. In conclusion, polymorphic STR DNA markers are useful for determining the numbers of chromosome 21 in fetal cells. The high sensitivity and automation of the procedures suggest a good prospect for use of this method in prenatal detection of fetal Down syndrome. However, this is a preliminary investigation and a large-scale study is necessary to validate the clinical application of this protocol.     

应用分子生物学技术产前诊断Down综合征

目的 探讨应用PCR分子生物学方法产前诊断Down综合征（Down syndrome,DS)。方法 取产前诊断病例：羊水100例，绒毛16例。提取DNA，PCR扩增21号染色体的6个多态位点，电泳，膜转移，等位基因位点分析，诊断。结果 正常人为两种带型：杂合型显示两条带，纯合型一条带。Down综合征患者为三种带型：完全杂合型显示三条带，半杂合型两条带（信号增强的2：1带），纯合型一条带。100例羊水中2例阳性，16例绒毛标本中1例阳性，3例患者，至少有2个位点检出三个等 基因，患者为2个位点时，表现2：1带型；无一例正常检出三个等位基因。所有结果均与细胞染色体核型检查相符。结论 本分子生物学方法产前诊断DS简便、快速、可行，是一种值得推广的方法。     

应用荧光原位杂交产前诊断未培养羊水细胞非整倍体

目的探讨荧光原位杂交(fluorescenceinsituhybridization,FISH)诊断未培养羊水细胞非整倍体的临床应用价值。方法对55例孕16～32周未培养羊水细胞进行FISH快速产前诊断,应用多色FISH对另4条染色体(X、Y、13号和18号)进行检测。以经母腹穿刺取胎血常规核型分析作为FISH检测结果对照。结果被检55例羊水未培养细胞均获得诊断结果,发现两例异常胎儿。1例为标准型21三体;另1例为21三体嵌合体。FISH检测与常规核型分析结果一致。结论FISH检测未培养羊水细胞非整倍体具有快速、简便、所用样本量少的优势,结果准确可靠,可达到产前诊断要求,有较大临床应用价值。     

应用荧光原位杂交快速产前诊断唐氏综合征

目的建立稳定的荧光原位杂交(fluorescence in situ hybridization,FISH)技术并用于唐氏综合征的产前诊断.方法对126例孕17w～24w未培养羊水细胞进行FISH快速产前诊断,以培养羊水细胞常规G显带核型分析作为FISH检测结果对照.结果被检126例羊水未培养细胞均获得诊断结果,发现4例异常胎儿.3例为标准型唐氏综合征;另1例为嵌合体.FISH检测与常规核型分析结果一致.结论FISH用于唐氏综合征产前诊断具有快速、简便、所用样本量少的优势,结果准确可靠,可达到产前诊断要求,有较大临床应用价值.     

Rapid prenatal detection of down and edwards syndromes by fluorescent polymerase chain reaction with short tandem repeat markers

Chromosome analysis is the main tool for the prenatal diagnosis of trisomies but requires great technical expertise and time consuming manual procedures. Recently, alternative methods, which provide rapidity and accuracy, without culture, have been developed for pregnant women requiring rapid decisions for termination. In this study, multiplex fluorescent polymerase chain reactions (F-PCRs) were performed by the concurrent use of short tandem repeat (STR) markers specific for the chromosomes 18 and 21. The aims of this investigation were to evaluate the clinical usefulness of this assay for rapid prenatal detection of Down and Edwards syndromes and then to accumulate the basic data for clinical application. F-PCRs were carried out using DNA extracted from amniotic fluid and peripheral blood derived from 47 normal karyotypes, 23 Down and 8 Edwards syndrome patients. Fluorescent intensities of the PCR products were then calculated. Normal samples displayed diallelic peaks for each STR marker. Reference ranges of peak area ratios were 1.0 - 1.4 for D21S11, 1.0 - 1.5 for D21S1412 and 1.0 - 1.3 for D18S535 and D18S51. Down and Edwards syndromes showed characteristic triallelic peaks of similar intensity corresponding to 3 different alleles or characteristic diallelic peaks. The sensitivity, specificity and efficiency of the assay for detecting Down and Edwards syndromes were 96.7%, 93.6% and 94.8%, respectively. In conclusion, these results show that F-PCR rapidly detects Down and Edwards syndromes with high accuracy and provides normal reference ranges of peak area ratios. However, the presence of false results (4 out of 77 cases) and the possibility of anomalies other than trisomies 21 and 18 do not permit F-PCR to substitute for chromosome analysis.