孕妇外周血胎儿游离DNA在产前筛查胎儿染色体非整倍体疾病中的价值

目的探讨孕妇外周血胎儿游离DNA在产前筛查胎儿染色体非整倍体疾病中的临床应用价值。方法接受产前诊断孕12~26周孕妇4 300例,采集外周血提取胎儿游离DNA,应用高通量测序技术检测风险值,对检测结果提示高风险者进一步行羊水穿刺胎儿染色体核型分析及基因芯片检测,对检测结果提示低风险者电话随访至分娩。结果胎儿游离DNA高通量测序检测提示高风险者45例,其中21-三体综合征29例,18-三体综合征11例,13-三体综合征5例;1例13-三体综合征羊水穿刺胎儿染色体核型分析未见异常,基因芯片检测发现孕妇13号染色体存在微重复,余44例高风险妊娠均经羊水穿刺胎儿染色体核型分析证实;胎儿游离DNA高通量测序提示低风险4 255例,其中3 008例完成随访,新生儿未见明显异常。结论孕妇外周血胎儿游离DNA产前筛查可高效、准确筛查胎儿染色体非整倍体疾病,且较介入性产前诊断易接受,具有较好的临床应用价值。     

胎儿染色体非整倍体无创产前基因检测技术在周口市的临床应用分析

目的探讨胎儿染色体非整倍体无创产前基因检测(non-invasive prenatal testing,NIPT)技术在周口市胎儿染色体非整倍体疾病筛查中的临床应用。方法选取2014年1月-2015年11月间,在周口市中心医院进行唐氏综合征筛查结果提示高风险(RISK1/275)、高龄孕妇(孕龄≥35岁)、有既往不良孕产史以及超声检查提示胎儿异常的共计829例孕妇,进行胎儿染色体非整倍体无创产前基因高通量测序分析,结果提示高风险的孕妇手术抽取羊水后核型分析。结果 612例唐氏筛查高风险孕妇组经外周血胎儿游离DNA检测结果提示高风险者共计7例(6例21-三体、1例18-三体);169例高龄孕妇组共检出1例18-三体结果高风险者;7例既往不良孕产史孕妇组检出1例21-三体结果高风险者;41例超声检查提示胎儿异常孕妇组共检出2例结果高风险(1例21-三体、1例13-三体)。NIPT结果提示21、18、13-三体异常高风险孕妇分别为8例、2例、1例,进一步行染色体核型分析的确诊例数分别为:8例、2例、1例,结果证实NIPT用于检测胎儿21-三体、18-三体、13-三体的敏感度为100%,特异度为100%,准确率100%,与染色体核型分析结果一致。结论周口市孕妇外周血游离胎儿DNA高通量测序分析可用于胎儿常见染色体非整倍体疾病的筛查,敏感度高、特异度强、准确率高应推广临床应用。     

无创胎儿染色体非整倍体基因检测在产前诊断中的临床应用价值分析

目的分析无创胎儿染色体非整倍体基因检测在产前诊断中的临床应用价值,探讨其临床适用性。方法选择从2015-01—2016-12于某院行产前检查的1 000例血清学产前筛查高风险,血清学筛查临界风险及高龄孕妇患者作为研究组,采用无创胎儿染色体非整倍体基因检测手段进行进一步筛查,对于检查结果阳性的孕妇进行羊水穿刺细胞染色体核型分析;另选择从2015-01—2016-12于某院行羊水细胞染色体核型分析的血清学产前筛查高风险,血清学筛查临界风险及高龄孕妇1 000例作为对照组。观察两组患儿检出率情况。结果研究组500例孕妇中,共有450例孕妇同意进行产前诊断,产前诊断参与率为90.0%(450/500),胎儿染色体非整倍体异常9例,占1.8%(9/500),其中胎儿染色体非整倍体异常检出8例,漏诊1例,检出率为88.9%(8/9);所有孕妇同时采用无创胎儿染色体非整倍体基因检测方法进行筛查,共有8名孕妇检测结果阳性,其中21-三体综合征异常胎儿6例,与羊水穿刺细胞染色体核型分析结果完全一致(100%),18-三体综合征异常胎儿2例,同样与羊水穿刺细胞染色体核型分析结果完全一致(100%)。仅1例无创胎儿染色体非整倍体基因检测阳性高龄产妇拒绝产前诊断,漏诊1例21-三体综合征异常胎儿;无创胎儿染色体非整倍体基因检测方法敏感度为100%(8/8),特异度为99.8%(499/500),假阳性率为0.2%(1/500),假阴性率为0。对照组500例孕妇中,共有440例孕妇同意进行产前诊断,产前诊断参与率为88.0%(440/500);胎儿染色体非整倍体异常9例,占1.8%(9/500),其中胎儿染色体异常诊断结果7例,漏诊2例,检出率为77.8%(7/9)。21-三体综合征异常胎儿6例,18-三体综合征异常胎儿1例。1例高龄产妇拒绝产前诊断,漏诊1例21-三体综合征异常胎儿,1例高龄体外受精-胚胎移植孕妇拒绝产前诊断,漏诊分娩1例21-三体综合征异常胎儿。结论无创胎儿染色体非整倍体基因检测手段的诊断灵敏度高,可以适当降低漏诊率,适合临床应用。     

孕妇血浆中胎儿游离 DNA 在唐氏综合征无创性产前诊断中的应用研究

目的：探讨应用孕妇血浆中游离胎儿高通量基因测序技术在无创性产前诊断中的可行性。方法对3368例孕妇进行中孕期血清学筛查的同时,筛查出的高风险病例平行进行 cffDNA 高通量测序;对需进行产前诊断者,同时进行胎儿染色体核型以及 MLPA 分析。结果中孕期三联血清学筛查3368例,血清学筛查21三体高危共347例,经高通量基因测序技术检测后结果为唐氏高危20例;经 MLPA 分析,结果得出347例标本中21-三体病例为20例;最后通过羊水细胞核型分析证实20例与无创基因检测结果一致。应用孕妇血浆中游离胎儿 DNA高通量基因测序技术诊断胎儿的21号染色体非整倍体异常的敏感度为100．00％（20/20）,特异性为100．00％（347/347）,假阳性率为0．00％（0/347）。结论无创性产前诊断技术具有无创、准确、快速的诊断优势,该技术具有良好的临床应用前景。     

无创产前基因测序在胎儿染色体非整倍体基因检测中的临床应用

目的探讨无创产前基因检测技术在胎儿染色体非整倍体疾病诊断中的检出效率及临床应用价值。方法回顾性分析2011年1月到2013年1月在广东省妇幼保健院就诊的孕妇,纳入标准为高龄妊娠,产前筛查高风险、B超显示胎儿异常等要求无创产前基因检测的孕12周以上的孕妇1 865例,通过母体外周血中胎儿游离DNA,应用无创产前基因检测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,对低风险胎儿均随访至出生后。结果实施无创产前基因检测1 865例,结果显示为高风险共21例,其中21-三体综合征高风险为14例,18-三体综合征高风险为5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14例21-三体综合征高风险中,13例确诊为21-三体综合征,另1例拒绝产前诊断,自行引产,无法确诊核型。检测出的5例18-三体综合征高风险经核型分析确诊为18-三体综合征,13-三体综合征无假阳性。所有低风险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21-三体综合征的敏感性为100%,准确性为92.9%。18-三体综合征和13-三体综合征的敏感性及准确性均为100%。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,其敏感性、准确性与染色体核型分析技术具有高度的一致性,能减少患儿的出生,快捷、安全、较介入性产前诊断易于接受,具有较高的临床实际应用价值。     

2 654例无创产前基因检测结果分析

目的探讨无创产前基因检测在胎儿染色体非整倍体疾病诊断中的临床应用价值。方法选择在该院行胎儿染色体非整倍体无创基因检测的单胎孕妇2 654例,对孕妇外周血中游离DNA进行高通量测序,对检测结果高风险者进行羊膜腔穿刺及胎儿染色体核型分析,对检测结果阴性者进行电话随访。结果 2 654例孕妇无创基因检测结果高风险29例,包括21-三体14例,18-三体6例,47,XXY 5例,45,XO 2例,常染色体异常1例,母体染色体异常1例。对29例高风险孕妇行羊膜腔穿刺羊水细胞染色体核型分析,结果显示21-三体11例,18-三体5例,性染色体异常4例。结论无创产前基因检测在诊断胎儿染色体非整倍体异常有较高的特异性和准确性,有较高的临床应用价值,但存在一定的假阳性,应掌握指征。     

无创DNA检测技术在常州市产前筛查中的应用

目的探讨无创DNA产前检查(NIPT)在胎儿染色体非整倍体疾病诊断中的应用价值。方法选取2 237例接受唐氏筛查的孕妇,对其外周血中游离胎儿DNA进行测序分析,阳性者进行羊水穿刺及染色体核型分析;阴性者行电话随访。结果 (1)无创DNA检测结果为阳性者共23例,包括21-三体15例、18-三体4例、13-三体1例,性染色体异常3例。(2)23例结果异常的孕妇,22例进行了羊水穿刺及染色体核型分析。结果显示无创DNA检测技术的检出率为100%,准确率86.4%。结论 NIPT对孕妇外周血中游离胎儿DNA的检测准确率达86.4%,其高准确性、无创伤性等优点将使其成为未来产前筛查的主力手段。     

无创产前基因检测胎儿染色体非整倍体的临床研究

目的探讨无创性产前基因检测胎儿染色体非整倍体在临床的应用。 方法选择2015年1～12月在我院产科门诊就诊的孕妇920例,先行无创产前基因检测（实验组）,对于无创产前基因检测高风险和中等风险者再行羊水或脐血穿刺染色体核型分析（对照组）。两组检测结果为阴性的孕妇,出生后进行随访,确定是否有无漏诊。通过两组阳性结果的比较及出生后的观察随访情况来衡量无创产前基因检测的检查胎儿非整倍体疾病的准确率,再来判断其临床应用价值。 结果实施无创产前基因检查920例,阳性结果为5例,其中21三体综合征为3例,18三体综合征为1例,13三体综合征为1例,阴性为915例;阳性结果以羊水或脐血穿刺染色体核型分析的结果为金标准进行结果对照,21 三体综合征有1 例假阳性,18 三体综合征与13 三体综合征无假阳性。检查结果阴性的孕妇,经产后随访无漏诊率。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,减少患儿的出生。该项技术具有最佳检测时间、无创取样、无流产风险、高灵敏度及准确度的特点,更适宜基层医院开展。      

荧光原位杂交技术及染色体核型分析在产前诊断中的应用

目的探讨羊水细胞荧光原位杂交(FISH)技术与染色体核型分析在产前诊断中的应用价值。方法对有产前诊断指征的491例孕妇在超声波引导下行羊膜穿刺术,抽取羊水进行细胞培养及染色体核型分析,同时用FISH技术检测羊水间期细胞13、18、21及X、Y染色体的数目。结果 491例孕妇羊水细胞培养核型分析检出异常核型19例,其中21-三体综合征7例、18-三体综合征3例、13-三体综合症1例、Turner综合征1例、超雌综合征2例、平衡易位1例、罗伯逊易位1例、9号染色体臂间倒位1例、15号染色体片段缺失1例、3号染色体未知来源附加片段1例。19例异常核型同时采用FISH技术检测,检出11例染色体数目异常和3例性染色体异常,有5例染色体结构异常未检出。结论 FISH技术能快速检测分析13、18、21非整倍体及性染色体数目异常,但FISH技术不能完全替代常规染色体核型分析。     

无创DNA产前检测在胎儿染色体非整倍体疾病筛查中的应用

目的探讨无创DNA产前检测技术在胎儿染色体非整倍体疾病产前筛查中的临床应用价值。方法回顾性分析2014年6月至2015年11月在广东省妇幼保健院医学遗传中心行无创DNA产前检测的5 946例孕妇的临床资料,并结合孕妇的血清学唐氏筛查、介入性产前诊断、妊娠结局随访等结果进行综合分析。结果 5 946例孕妇中,无创DNA产前检测提示62例异常,其中21-三体高风险17例,18-三体高风险10例,13-三体高风险3例,性染色体异常15例,其他染色体异常17例。经介入性产前诊断确诊21-三体综合征15例,18-三体综合征9例,13-三体综合征1例,性染色体异常10例,其他染色体异常1例。此外,5例无创DNA产前检测提示为三体高风险者,经穿刺确认结果为阴性,妊娠结局随访未见异常;2例无创DNA产前检测提示为阴性,而经穿刺确认结果为18-三体高风险者。该技术进行胎儿染色体非整倍体体筛查的灵敏度为92.59%,特异度为99.92%,假阳性率为0.08%,假阴性率为7.41%。结论无创DNA产前检测对胎儿染色体非整倍体疾病的检出率高,其在临床的推广应用对出生缺陷率的降低有重要意义。     

Systematic search for placental DNA-methylation markers on chromosome 21: toward a maternal plasma-based epigenetic test for fetal trisomy 21

BACKGROUND: The presence of fetal DNA in maternal plasma represents a source of fetal genetic material for noninvasive prenatal diagnosis; however, the coexisting background maternal DNA complicates the analysis of aneuploidy in such fetal DNA. Recently, the SERPINB5 gene on chromosome 18 was shown to exhibit different DNA-methylation patterns in the placenta and maternal blood cells, and the allelic ratio for placenta-derived hypomethylated SERPINB5 in maternal plasma was further shown to be useful for noninvasive detection of fetal trisomy 18. METHODS: To develop a similar method for the noninvasive detection of trisomy 21, we used methylation-sensitive single nucleotide primer extension and/or bisulfite sequencing to systematically search 114 CpG islands (CGIs)-76% of the 149 CGIs on chromosome 21 identified by bioinformatic criteria-for differentially methylated DNA patterns. The methylation index (MI) of a CpG site was estimated as the proportion of molecules methylated at that site. RESULTS: We identified 22 CGIs which were shown to contain CpG sites that were either completely unmethylated (MI = 0.00) in maternal blood cells and methylated in the placenta (MI range, 0.22-0.65), or completely methylated (MI = 1.00) in maternal blood cells and hypomethylated in the placenta (MI range, 0.00-0.75). We detected, for the first time, placental DNA-methylation patterns on chromosome 21 in maternal plasma during pregnancy and observed their postpartum clearance. CONCLUSION: Twenty-two (19%) of the 114 studied CGIs on chromosome 21 showed epigenetic differences between samples of placenta and maternal blood cells; these CGIs may provide a rich source of markers for noninvasive prenatal diagnosis.     

Noninvasive prenatal detection of fetal trisomy 18 by epigenetic allelic ratio analysis in maternal plasma: Theoretical and empirical considerations

BACKGROUND: The discovery of cell-free fetal DNA in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis. However, the use of maternal plasma fetal DNA for the direct detection of fetal chromosomal aneuploidies has not been reported. We postulate that the aneuploidy status of a fetus could be revealed by an epigenetic allelic ratio approach, i.e., by analyzing the allelic ratio of a single-base variation present within DNA molecules exhibiting a placental-specific epigenetic signature in maternal plasma. METHODS: Placental-derived fetal-specific unmethylated maspin (SERPINB5) promoter sequences on human chromosome 18 were detectable in placental-maternal DNA mixtures and in maternal plasma by bisulfite modification followed by methylation-specific PCR (MSP) and primer extension. The ratios between the extension products of the 2 alleles were calculated for heterozygous placentas, placental-maternal blood cell DNA mixtures, and maternal plasma samples. The allelic ratios were compared between pregnancies carrying trisomy 18 and euploid fetuses. RESULTS: The epigenetic allelic ratios of all tested trisomy 18 samples deviated from the reference range obtained from euploid samples (placental DNA, 1.135 to 2.052; placental-maternal DNA mixtures, 1.170 to 1.985; maternal plasma, 0.330 to 3.044; without skew correction on the raw mass spectrometric data). A theoretical model was established and validated that predicted that a minimum of 200 copies of genomic DNA after bisulfite conversion were required for distinguishing euploid and aneuploid fetuses with confidence. CONCLUSION: Epigenetic allelic ratio analysis of maternal plasma DNA represents a promising approach for noninvasive prenatal diagnosis of fetal chromosomal aneuploidies.     

第二代测序技术与无创产前诊断

孕妇外周血中胎儿游离DNA（cellfreefetalDNA,cffDNA）的发现开辟了无创产前诊断的新篇章,借助各种分子诊断技术针对cffDNA进行胎儿染色体疾病、遗传性疾病以妊娠相关疾病的研究迅速成为热点。以高通量、自动化为显著特征的第二代测序（next—generationsequencing,NGS）技术诞生．极大加速了cffDNA的实验室研究进展。目前基于NGS平台,建立的胎儿21／18／13三体综合征的产前基因诊断技术已应用于临床。其他如性染色体非整倍体、双胎妊娠染色体非整倍体、胎儿染色体结构异常疾病以及孟德尔单基因遗传病的研究也因NGS的出现获得了显著的进步。本文就NGS的基本原理、cffDNA的生理特性及NGS在无创产前诊断研究中的进展进行综述。     

Noninvasive prenatal diagnosis of fetal chromosomal aneuploidies by maternal plasma nucleic acid analysis.

BACKGROUND: The discovery of circulating cell-free fetal nucleic acids in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis. The potential application of this technology for the noninvasive prenatal detection of fetal chromosomal aneuploidies is an aspect of this field that is being actively investigated. The main challenge of work in this area is the fact that cell-free fetal nucleic acids represent only a minor fraction of the total nucleic acids in maternal plasma. Methods and RESULTS: We performed a review of the literature, which revealed that investigators have applied methods based on the physical and molecular enrichment of fetal nucleic acid targets from maternal plasma. The former includes the use of size fractionation of plasma DNA and the use of the controversial formaldehyde treatment method. The latter has been achieved through the development of fetal epigenetic and fetal RNA markers. The aneuploidy status of the fetus has been explored through the use of allelic ratio analysis of plasma fetal epigenetic and RNA markers. Digital PCR has been shown to offer high precision for allelic ratio and relative chromosome dosage analyses. CONCLUSIONS: After a decade of work, the theoretical and practical feasibility of prenatal fetal chromosomal aneuploidy detection by plasma nucleic acid analysis has been demonstrated in studies using small sample sets. Larger scale independent studies will be needed to validate these initial observations. If these larger scale studies prove successful, it is expected that with further development of new fetal DNA/RNA markers and new analytical methods, molecular noninvasive prenatal diagnosis of the major chromosomal aneuploidies could become a routine practice in the near future.     

无创产前基因检测技术的临床应用价值评价

目的探讨无创产前基因检测技术在筛查胎儿染色体非整倍体中的作用。 方法选择需做产前诊断的74名孕妇,采用高通量基因测序技术检测母体血浆胎儿游离DNA,分析胎儿染色体拷贝数。依据患者产前诊断的临床指征分为4个组(高龄妊娠组、母体血清筛查高危组、B超胎儿异常组及生育过21-三体患儿组),计算每组高危患者的比率。对无创产前基因检测显示胎儿染色体非整倍体高危的11例患者,行羊膜腔穿刺进行胎儿染色体核型分析。 结果在各组中显示胎儿染色体非整倍体高危的比率是：高龄妊娠组10.50%(4/38),母体血清高危组17.40%(4/23),B超异常组30.00%,生育过21三体患儿组0.00%(0/3),总高危率14.90%(11/74)。在11例无创产前基因检测显示胎儿染色体非整倍体高危患者中,9例的无创产前筛查结果与胎儿染色体核型一致,一致率81.80%。2例患者为假阳性。 结论无创产前基因检测技术是一种筛查胎儿染色体非整倍体的有效方法,其在胎儿染色体异常疾病的产前检测中具有广泛的应用前景。     

无创产前基因检测技术的临床应用价值

应用母血中胎儿游离的DNA检测胎儿非整倍体技术已开始应用于临床,这一技术与传统的产前筛查和诊断技术相比,具有无创、快速、准确等优点,它是产前筛查和诊断领域的一次革命。本文通过对比分析现有研究资料,评估无创产前基因检测技术在临床应用价值。     

Fetal DNA in maternal plasma: biology and diagnostic applications

BACKGROUND: Molecular analysis of plasma DNA during human pregnancy has led to the discovery that maternal plasma contains both fetal and maternal DNA. This valuable source of fetal DNA opens up new possibilities for noninvasive prenatal diagnosis. APPROACH: Published data from the last 3 years demonstrating the feasibility and utility of analyzing fetal DNA in maternal plasma are reviewed. CONTENT: The detection of fetal DNA in maternal plasma is much simpler and more robust than detecting fetal nucleated cells in maternal blood, and does not require prior enrichment. This approach has been shown to have application in the prenatal diagnosis of fetal rhesus D status, sex-linked disorders, and other paternally inherited genetic disorders. Abnormal fetal DNA concentrations in maternal plasma and serum have been found in common pregnancy-associated disorders, including preterm labor and preeclampsia, as well as in pregnancies complicated by fetal trisomy 21. After delivery, fetal DNA is cleared rapidly from maternal plasma, with a half-life in the order of minutes. These clearance kinetics exhibit an important difference from fetal cell clearance, where long-term persistence has been demonstrated. SUMMARY: It has been only 3 years since fetal DNA was first detected in maternal plasma, and much remains to be learned about the biology of this phenomenon. In addition, additional diagnostic applications beyond those discussed here can be expected in the near future.