孕妇血浆游离DNA高通量测序用于胎儿性染色体非整倍体检测的初步探讨

摘要：目的：初步探讨孕妇血浆游离DNA高通量测序用于产前胎儿性染色体非整倍体检测的效果及临床可行性。 方法：2011年至2012年收集早、中孕期单胎孕妇5 540例,在知情同意的原则下采集外周血血浆进行游离DNA的高通量测序检测,通过生物信息学分析,获得测序结果;对测序检出的性染色体非整倍体患者行羊水穿刺,进行染色体G显带分析。 结果：5 540例样本中测序方法共检出10例性染色体非整倍体,其中6例与G带核型分析结果一致,包括3例45,X,1例47,XXY,2例47,XYY,其余4例G带核型正常。 结论：孕母血浆游离DNA高通量测序可对性染色体非整倍体胎儿进行无创性产前检测,但存在假阳性,还需进一步完善实验方案以提高检测效果。     

Illumina测序技术在母血检测胎儿非整倍体中应用

目的研究Illumina测序技术在母血中检测胎儿非整倍体的可行性,及其在无创性产前诊断中的应用前景。方法 68例孕12-39周具有产前诊断指征的单胎妊娠孕妇抽取外周血进行离心、提取血浆中游离DNA,运用Illumina Hiseq2000测序技术进行DNA测序及统计分析。结果 68例孕妇通过Illumina测序技术检测出3例21三体,2例18三体、1例13三体及1例47,XYY。因为濒死胎儿羊水脱落细胞活力极低而致羊水培养失败,传统型染色体核型分析未检测出1例21三体。结论 Illumina测序作为一种无创性产前诊断技术,可准确地筛查21、18、13、X、Y等染色体非整倍体异常,具有安全、准确率高及假阳性率低的优点,值得临床推广。     

Introducing WISECONDOR for noninvasive prenatal diagnostics

Noninvasive prenatal testing is a relatively new screening method for the detection of fetal chromosome abnormalities using next-generation sequencing (NGS) of fetal DNA in maternal blood. Recently, the introduction of a new tool called WIthin SamplE COpy Number aberration DetectOR (WISECONDOR) marked a new era in prenatal screening. WISECONDOR detects copy number aberrations at a resolution that is almost comparable to classic karyotyping and requires only shallow sequencing, making noninvasive prenatal screening cost-effective. This emphasizes the role of NGS in the daily clinical practice of prenatal diagnosis and will require reorganization of clinical genetics laboratories to accommodate NGS. For prenatal diagnostics, WISECONDOR introduces an exciting development that will substantially improve the information provided to pregnant couples regarding their fetus’s wellbeing.     

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。     

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。     

无创产前DNA检测在超声软指标异常胎儿染色体筛查中的应用及妊娠结局分析

目的 分析无创产前DNA检测（NIPT）在超声软指标（USM）异常胎儿染色体筛查中的应用及相应妊娠结局。方法纳入在我院经超声检查确认为USM异常的4 210例胎儿,均进行NIPT检测,并经染色体核型检测明确染色体情况。分析NIPT对不同染色体异常类型胎儿诊断的阳性预测值、灵敏度和特异度。比较不同USM异常类型和异常数目胎儿的NIPT及染色体核型检查结果。结果 NIPT检测高风险47例（1.12%）。NIPT对21-三体诊断的阳性预测值明显高于性染色体异常、13-三体和其他（P<0.05）。NT增厚、鼻骨缺失胎儿的NIPT高风险率及染色体异常率均较高。USM异常≥3项下NIPT诊断的阳性预测值均高于单项和双项异常,但差异无统计学意义（P>0.05）。结论 在NT增厚和鼻骨缺失等USM异常胎儿染色体筛查中,NIPT检测高风险率随着USM异常指标数目的增加而提高。对于NIPT低风险的USM异常者,仍需保持妊娠期随访,以减少漏诊,促使出生人口质量的提升。     

介入性核型检测联合超声在无创胎儿非整倍体异常病例中的应用

目的探讨介入性核型检测联合超声在胎儿无创非整倍体筛查异常病例中的应用。 方法收集2015年10月至2017年12月在徐州市中心医院产前诊断中心进行无创产前基因检测（NIPT）的单胎孕妇2640例为研究对象,年龄18~43岁,孕周13~25周,对检测42例异常染色体孕妇进行产前诊断并对妊娠结局进行跟踪统计分析。介入性核型检查与NIPT对胎儿染色体异常结果检测效能的比较采用McNemar χ²检验和Kappa一致性检验。 结果NIPT异常者42例：其中31例常染色体异常、10例性染色体异常及同时有常染色体及性染色体异常1例,常染色体异常包括：17例21-三体高风险,9例提示18-三体高风险,染色体7-三体、15-三体及13-三体各1例,7号染色体重复51Mb 1例,16号染色体异常1例;10例性染色体异常中45,XO 6例;47,XYY 2例,47,XXX 1例,性染色体XX与XXX嵌合1例。42例中1例放弃产前诊断直接引产,36例羊水穿刺,5例脐静脉穿刺,确诊21-三体14例、18-三体7例和47,XYY 1例,余320~400染色体条带水平未发现异常,其中有12例21-三体和7例18-三体胎儿有超声结构改变,余无超声结构改变,共22例引产,1例流产,19例新生儿结局良好。NIPT对胎儿染色体异常阳性率明显高于介入性核型检查（P<0.05）。 结论NIPT对21-三体和18-三体检出率较高,但对于常染色体和性染色体仍存在一定的假阳性,NIPT发现异常的孕妇需进行胎儿结构超声及介入性核型检查,避免对无辜胎儿的伤害。     

Screening,prenatal diagnosis,and prenatal decision for sex chromosome aneuploidy

Objective: To assess the performance of non-invasive prenatal testing (NIPT) in screening sex chromosome aneuploidy (SCA), and explore prenatal decision-making in NIPT positive cases.

Methods: The study retrospectively analyses singleton pregnancies who underwent NIPT screening. Clinical data, diagnostic results, and pregnancy outcomes were also collected.

Results: There were 140 positive screens for SCA, including 62 cases of 45,X, 29 cases with 47,XXX, 28 cases of 47,XXY, 20 cases of 47,XYY, and one case of lower X chromosome. Karyotypic information was available in 103 cases. The positive predictive value was 26.09% for 45,X, 85.00% for 47,XXX, 85.00% for 47,XXY, and 68.75% for 47,XYY. The termination rates of 45,X, 47,XXX, 47,XXY, 47,XYY were 83.33%, 26.67%, 82.35%, and 54.54%, respectively (not including mosaic cases).

Conclusion: Our findings demonstrated that the NIPT performed better in predicting sex chromosome trisomies than monosomy X even though false-positive cases do exist in NIPT. For prenatal decisions, pregnancies with diagnoses of fetal 45,X and 47,XXY were terminated more often than those with 47,XXX, 47,XYY. To better guide positive screening pregnancies, pre- and post-test counseling are essential in telling patients the benefits and limitations of the test, comforting their anxiety and giving them the choice for further diagnosis and pregnancy decision.     

染色体特异位点筛选方法在无创产前检测中的应用

目的建立一种基于染色体特异位点测序进行无创产前检测的方法,以替代目前传统的基于全基因组测序的无创产前检测技术。方法采集200例已知胎儿核型的孕妇血浆样本,通过数据库筛选挑选出13、18、21号染色体上特异性的位点,通过探针捕获的方式进行特异性片段的捕获,针对特异性片段进行测序分析,通过Z值计算来判断是否存在染色体非整倍体异常。结果染色体特异位点筛选法检出7例21三体胎儿、3例18三体胎儿,1例13三体胎儿,结果与全基因组高通量测序法一致。结论基于染色体特异位点测序法具有检测成本低、检测通量高的优势,有望替代全基因组高通量测序法进行无创产前筛查。     

Prenatal diagnosis of a 46,XX male following noninvasive prenatal testing

Case report involving a normal female by NIPT with male external genitalia on routine fetal morphology assessment. QF‐PCR, CGH microarray, and FISH revealed an unbalanced translocation, involving the short arms of the X and Y chromosomes. This case demonstrates the possible limitations of correctly identifying sex chromosome abnormalities via NIPT.     

Reliable noninvasive prenatal testing by massively parallel sequencing of circulating cell-free DNA from maternal plasma processed up to 24 h after venipuncture

Objectives

Circulating cell-free fetal DNA (ccffDNA) in maternal plasma is an attractive source for noninvasive prenatal testing (NIPT). The amount of total cell-free DNA significantly increases 24 h after venipuncture, leading to a relative decrease of the ccffDNA fraction in the blood sample. In this study, we evaluated the downstream effects of extended processing times on the reliability of aneuploidy detection by massively parallel sequencing (MPS).

Design and methods

Whole blood from pregnant women carrying normal and trisomy 21 (T21) fetuses was collected in regular EDTA anti-coagulated tubes and processed within 6 h, 24 and 48 h after venipuncture. Samples of all three different time points were further analyzed by MPS using Z-score calculation and the percentage of ccffDNA based on X-chromosome reads.

Results

Both T21 samples were correctly identified as such at all time-points. However, after 48 h, a higher deviation in Z-scores was noticed. Even though the percentage of ccffDNA in a plasma sample has been shown previously to significantly decrease 24 h after venipuncture, the percentages based on MPS results did not show a significant decrease after 6, 24 or 48 h.

Conclusions

The quality and quantity of ccffDNA extracted from plasma samples processed up to 24 h after venipuncture are sufficiently high for reliable downstream NIPT analysis by MPS. Furthermore, we show that it is important to determine the percentage of ccffDNA in the fraction of the sample that is actually used for NIPT, as downstream procedures might influence the fetal or maternal fraction.     

ERG甲基化位点检测技术在无创性产前诊断中的应用

目的通过检测和分析游离胎儿DNA的ERG基因在不同孕期中浓度的变化,探讨利用ERG甲基化位点检测技术应用于无创性产前诊断的可行性。方法随机选取健康妊娠妇女早孕组、中孕组、晚孕组各30例。采用HpaⅡ、MspⅠ分别对血浆中提取的游离DNA酶切后进行SYBR PCR反应,通过检测ERG基因甲基化位点,定量分析不同孕期的孕妇血浆中游离胎儿DNA浓度。结果游离胎儿DNA的ERG基因在孕妇血浆中的浓度随着孕周的增长而升高。各孕周组的母血浆中ERG基因浓度（LG copies/mL）中位数分别为5.38,6.10和7.04（χ2=75.104,P〈0.01）。结论本研究证实了游离胎儿DNA的ERG基因序列上CCGG位点存在甲基化的特性。进一步确定了ERG基因作为胎儿DNA的标记物应用于无创性产前诊断的可行性。     

Detecting mitochondrial mutations associated with aminoglycoside ototoxicity by noninvasive prenatal testing

ObjectivesNumerous diseases and disorders are associated with mitochondrial DNA (mtDNA) mutations, among which m.1555A > G and m.1494C > T mutations in the 12 S ribosomal RNA gene contribute to aminoglycoside‐induced and nonsyndromic hearing loss worldwide.MethodsA total of 76,842 qualified non‐invasive prenatal (NIPT) samples were subjected to mtDNA mutation and haplogroup analysis.ResultsWe detected 181 m.1555A > G and m.1494C > T mutations, 151 of which were subsequently sequenced for full‐length mitochondrial genome verification. The positive predictive values for the m.1555A > G and m.1494C > T mutations were 90.78% and 90.00%, respectively, a performance comparable to that attained with newborn hearing screening. Furthermore, mitochondrial haplogroup analysis revealed that the 12 S rRNA 1555A > G mutation was enriched in sub‐haplotype D5[p = 0, OR = 4.6706(2.81–7.78)].ConclusionsOur findings indicate that the non‐invasive prenatal testing of cell‐free DNA obtained from maternal plasma can successfully detect m.1555A > G and m.1494C > T mutations.     

产前超声及无创基因筛查诊断胎儿性染色体异常

目的 探讨超声及无创产前基因筛查（NIPT）诊断胎儿性染色体异常的价值。方法 回顾性分析8 792名高危孕妇,分析产前超声及NIPT对胎儿性染色体异常的检出率,观察性染色体异常胎儿妊娠结局。结果 共检出144胎（144/8 792,1.64%）性染色体异常胎儿。其中性染色体数目异常139胎（139/8 792,1.58%）,包括45,X（Turner综合征）32胎、45,X嵌合体22胎、47,XXY（Klinefelter综合征）44胎、47,XXY嵌合体3胎、47,XXX 23胎、47,XYY 11胎、其他数目异常3胎及45,X[15]/46,XX[40]男性性反转1胎;性染色体结构异常5胎（5/8 792,0.06%）。超声检出73胎（73/144,50.69%）异常。77胎接受NIPT筛查,其中75胎（75/77,97.40%）性染色体异常。32胎45,X胎儿中,31胎超声可见异常,其中28胎表现为颈部水囊瘤,后均引产;112胎其他类型性染色体异常胎儿中,42胎（42/112,37.50%）继续妊娠。结论 NIPT对检出性染色体异常具有重要价值;产前超声筛查发现颈部水囊瘤时,应高度警惕45,X。     

利用孕妇血浆中胎儿游离DNA进行无创伤性产前基因诊断的研究进展

孕妇血浆中胎儿游离DNA,源于胎儿细胞和/或胎盘的凋亡,经核酸内切酶选择性地剪切为313 bp以下的短片段分子,因相对含量丰富,成为了当前无创伤性产前分子遗传诊断中胎儿DNA的重要来源,业已开展了胎儿性别鉴定、RhD阴性孕妇的Rh（D）基因检测、胎儿非整倍体病的诊断、STR遗传标记检测等应用研究。根据胎儿游离DNA的浓度、纯度、分子片段大小分布的特征和检测的靶基因,采用相应的分子基因诊断策略和实验设计,限制扩增产物的片段长度,有助于提高无创伤性产前胎儿分子遗传诊断的成功率。当前,大规模并行基因组测序技术为直接利用胎儿游离DNA进行无创伤性产前基因诊断开辟了新途径。     

男性胎儿DNA含量低的孕妇的无创产前检测

目的探讨外周血中胎儿DNA含量低的孕妇的无创产前检测(NIPT)。方法回顾分析2015年4月至2016年3月间在佛山市妇幼保健院行NIPT的3 240例孕妇实验数据与随访资料,根据其Y染色体z值,筛选出胎儿为男性且胎儿DNA含量低于8%的样品共150例,利用琼脂糖凝胶电泳富集法提高胎儿DNA含量,进行NIPT,对比非整倍体筛查结果的准确率。结果琼脂糖凝胶电泳富集法将样品中的胎儿DNA含量从平均5%提高到9.2%。对比胎儿DNA含量提高前后的NIPT结果是一致的。结论当胎儿DNA含量高于5%时,胎儿DNA含量不会影响NIPT结果的准确率。     

基于游离RNA的无创性产前诊断研究进展

孕妇血浆血清中游离RNA作为一种新的胎儿遗传信息材料给无创性产前诊断带来了新的契机。已经证实,游离胎儿RNA分子主要来源于胎盘,且稳定存在于母体血循环中,易于检测。同时,其由于无需依赖胎儿性别或父源性多态性位点而具有十分明显的应用优势。目前,已经有研究将血浆血清中游离RNA与胎儿非整倍体、宫内发育迟缓以及子痫前期等妊娠相关疾病联系起来,并且取得了十分可喜的研究成果。     

产前超声在单脐动脉及合并胎儿畸形中的诊断价值

目的研究产前超声在单脐动脉及合并胎儿畸形中的诊断价值。方法纳入单脐动脉病例113例,根据是否合并胎儿畸形将其分为对照组(67例,单纯性单脐动脉)和观察组(46例,单脐动脉合并胎儿畸形)。统计观察组胎儿的畸形类型分布、两组胎儿的染色体异常情况及围产资料。结果观察组胎儿中,以心血管系统、肢体和泌尿系统畸形为主要的畸形类型。观察组染色体异常11例(23.91%),8例18-三体,1例13-三体,2例染色体结构异常;观察组的染色体异常率显著高于对照组(P<0.05)。两组的妊娠结局、早产率、胎龄、新生儿体质量比较,差异具有统计学意义(P<0.05)。结论产前超声有助于提高单脐动脉胎儿的临床诊断率,对于单脐动脉合并胎儿畸形,建议进一步开展染色体检查。单纯性单脐动脉胎儿大多妊娠结局较好,然而单脐动脉合并畸形胎儿的早产、低出生体重发生率有所增加,应加强孕期监测。