Investigation of maternal blood enriched for fetal cells: role in screening and diagnosis of fetal trisomies.

Prenatal diagnosis of chromosomal abnormalities relies on assessment of risk followed by invasive testing in the group with highest risk. Assessment of risk by a combination of maternal age and fetal nuchal translucency and invasive testing in the 5% of the population with the highest risk would identify about 80% of trisomy 21 pregnancies. Preliminary reports suggest that chromosomal abnormalities can also be diagnosed by fluorescent in situ hybridization (FISH) in maternal blood enriched for fetal cells. This study examines the potential role of this method on the prenatal diagnosis of fetal trisomies. Maternal blood was obtained before invasive testing in 230 pregnancies at 10-14 weeks of gestation. After enrichment for fetal cells, by triple density centrifugation and anti-CD71 magnetic cell sorting, FISH was performed and the proportion of cells with positive signals in the chromosomally normal and abnormal groups was determined. Fetal karyotype was normal in 150 cases and abnormal in 80 cases, including 36 with trisomy 21. Using a 21 chromosome-specific probe, three-signal nuclei were present in at least 5% of the enriched cells from 61% of the trisomy 21 pregnancies and in none of the normal pregnancies. For a cut-off of 3% of three-signal nuclei the sensitivity for trisomy 21 was 97% for a false positive rate of 13%. Similar values were obtained in trisomies 18 and 13 using the appropriate chromosome-specific probe. Examination of fetal cells from maternal blood may provide a noninvasive prenatal diagnostic test for trisomy 21 with the potential of identifying about 60% of affected pregnancies. Alternatively, this technique can be combined with maternal age and fetal nuchal translucency as a method of selecting the high-risk group for invasive testing. Potentially, 80% of trisomy 21 pregnancies could be identified after invasive testing in less than 1% of the pregnant population.     

Investigation of maternal blood enriched for fetal cells: Role in screening and diagnosis of fetal trisomies

Prenatal diagnosis of chromosomal abnormalities relies on assessment of risk followed by invasive testing in the group with highest risk. Assessment of risk by a combination of maternal age and fetal nuchal translucency and invasive testing in the 5% of the population with the highest risk would identify about 80% of trisomy 21 pregnancies. Preliminary reports suggest that chromosomal abnormalities can also be diagnosed by fluorescent in situ hybridization (FISH) in maternal blood enriched for fetal cells. This study examines the potential role of this method on the prenatal diagnosis of fetal trisomies. Maternal blood was obtained before invasive testing in 230 pregnancies at 10–14 weeks of gestation. After enrichment for fetal cells, by triple density centrifugation and anti-CD71 magnetic cell sorting, FISH was performed and the proportion of cells with positive signals in the chromosomally normal and abnormal groups was determined. Fetal karyotype was normal in 150 cases and abnormal in 80 cases, including 36 with trisomy 21. Using a 21 chromosome-specific probe, three-signal nuclei were present in at least 5% of the enriched cells from 61% of the trisomy 21 pregnancies and in none of the normal pregnancies. For a cut-off of 3% of three-signal nuclei the sensitivity for trisomy 21 was 97% for a false positive rate of 13%. Similar values were obtained in trisomies 18 and 13 using the appropriate chromosome-specific probe. Examination of fetal cells from maternal blood may provide a noninvasive prenatal diagnostic test for trisomy 21 with the potential of identifying about 60% of affected pregnancies. Alternatively, this technique can be combined with maternal age and fetal nuchal translucency as a method of selecting the high-risk group for invasive testing. Potentially, 80% of trisomy 21 pregnancies could be identified after invasive testing in less than 1% of the pregnant population. Am. J. Med. Genet. 85:66–75, 1999. © 1999 Wiley-Liss, Inc.     

2473例双胎妊娠的无创产前检测结果分析

目的:分析探讨无创产前检测(non-invasive prenatal testing,NIPT)对于双胎妊娠胎儿非整倍体的检测价值。方法:选取2016年1月至2019年12月在本中心接受NIPT检测的2473例双胎孕妇,利用高通量测序和生物信息学分析测算胎儿染色体非整倍体的风险率,为高风险孕妇提供羊膜腔或绒毛穿刺,并...     

无创产前检测对于胎儿染色体拷贝数变异的检测价值

目的:探讨无创产前检测(non-invasive prenatal testing,NIPT)对于胎儿染色体拷贝数变异(copy number variations, CNVs)的检测价值。方法:收集18 661例接受NIPT检测的孕妇的临床资料,为提示胎儿携带CNVs的孕妇提供羊水染色体核型或/及染色体微阵列分析,并...     

Noninvasive prenatal testing using a novel analysis pipeline to screen for all autosomal fetal aneuploidies improves pregnancy management

Noninvasive prenatal testing by massive parallel sequencing of maternal plasma DNA has rapidly been adopted as a mainstream method for detection of fetal trisomy 21, 18 and 13. Despite the relative high accuracy of current NIPT testing, a substantial number of false-positive and false-negative test results remain. Here, we present an analysis pipeline, which addresses some of the technical as well as the biologically derived causes of error. Most importantly, it differentiates high z-scores due to fetal trisomies from those due to local maternal CNVs causing false positives. This pipeline was retrospectively validated for trisomy 18 and 21 detection on 296 samples demonstrating a sensitivity and specificity of 100%, and applied prospectively to 1350 pregnant women in the clinical diagnostic setting with a result reported in 99.9% of cases. In addition, values indicative for trisomy were observed two times for chromosome 7 and once each for chromosomes 15 and 16, and once for a segmental trisomy 18. Two of the trisomies were confirmed to be mosaic, one of which contained a uniparental disomy cell line. As placental trisomies pose a risk for low-grade fetal mosaicism as well as uniparental disomy, genome-wide noninvasive aneuploidy detection is improving prenatal management.     

胎儿颈部半透明膜厚度测定筛查胎儿染色体异常

目的探讨孕早期筛查胎儿染色体异常的方案.方法 2241例孕龄在11～14w单胎妊娠的孕妇接受筛查.采用腹式或阴式B型超声波测量胎儿颈部半透明膜(NT)厚度;根据所测NT数据结合孕妇年龄由计算机算出胎儿染色体异常风险率.对所筛查出的高风险胎儿则进一步进行产前诊断(羊水细胞染色体核型分析).结果共筛查出26例染色体异常,包括Down综合征16例(61.54%)、性染色体数目异常6例(23.08%)、染色体结构异常4例(15.38%).所有接受筛查的孕妇中风险大于1/250者344例(15.35%);染色体异常检出率为80.77%,假阳性率为6.50%;21三体检出率为87.50%.结论孕早期NT 孕妇年龄二联筛查方案对孕早期临床筛查胎儿染色体异常有较好的实用价值.     

佛山地区产前筛查与产前诊断分析研究

目的佛山地区产前筛查与产前诊断分析研究。方法选择自2006年1月～2008年12月来本院进行产前检查的孕妇共41 656例,其中有2 9101例自愿行血清学筛查,孕周为15～25周,年龄21～42岁,平均年龄为25.73岁。有41 333例行超声筛查,孕周11～36周。对唐氏筛查及B超筛查结果为高风险的孕妇进行遗传咨询,建议进行产前诊断确诊。产前诊断的方法采用羊膜腔穿刺羊水细胞培养或经腹脐静脉穿刺脐血细胞培养,染色体检查采用G带染色。结果在血清筛查2 9101例孕妇中,筛查出高风险3227例,阳性率为11.1%。其中21三体高风险1287例,占4.4%;18三体高风险423例,占1.45%。在血清筛查高风险的3227例孕妇中,接受产前诊断者1065例,占33%（1065/3227）。染色体核型异常者100例,占12.49%,占高风险孕妇的4.12%（100/3227）。其中21三体19例,18三体2例,检出率为1.97%（21/1065）,占染色体核型异常的21%（21/100）。有41 333例行超声筛查,超声检查筛查出高风险851例,阳性率为2.06%。行产前诊断206例,染色体异常45例,占21.84%（45/206）,其中检查出21三体5例,18三体8例,13三体1例,占染色体异常的31.11%（14/45）。结论将孕妇年龄、血清学检测和超声筛查作为产前筛查唐氏综合征的方法,明显提高了筛查阳性率,通过产前筛查将高风险的人群筛查出来作产前诊断,减少了缺陷儿出生。     

Abnormal maternal serum levels of human chorionic gonadotropin free subunits in trisomy 18

We have measured maternal serum levels of free alpha and beta subunits of human chorionic gonadotropin between 8 and 12 weeks of gestation in 704 women at increased risk for trisomy. This group was studied because of advanced maternal age or a previous birth with chromosomal abnormality. All sera had been collected prior to chorion villus biopsy for prenatal diagnosis. Serum levels of free alpha and beta hCG were determined by specific monoclonal antibody-based immunoradiometric assays. Analysis of chorionic tissue showed that in 38 of 704 (5.4%) pregnancies the fetus had a chromosome abnormality. There were 8 fetuses with trisomy 18 (1.1%) and 9 (1.3%) with trisomy 21. In all pregnancies carrying a trisomy 18 fetus, we observed either high levels of free alpha hCG or low levels of free beta hCG or both. More importantly, the calculated ratio of free beta hCG/alpha hCG was less than 0.25 multiples of the median (MoM) in 6 of 8 (75%) trisomy 18 cases. Only 21 of 666 mothers (3.2%) carrying a normal fetus had a ratio less than 0.25 MoM (P less than 0.0001). There was no difference between this ratio in trisomy 21 and normal pregnancy. Thus, when adjusted for gestational age, a low free beta hCG/alpha hCG ratio in maternal serum indicates a pregnancy at high risk [RR = 72 (95% CI 32, 162)] for trisomy 18.     

Trisomies 13 and 18: population prevalences, characteristics, and prenatal diagnosis, metropolitan Atlanta, 1994-2003

In recent years, prenatal diagnosis and elective pregnancy termination have affected the reported birth prevalence of trisomies 13 and 18. We examined the prevalence and characteristics of these conditions using 1994-2003 data from a population-based surveillance system, the Metropolitan Atlanta Congenital Defects Program. Including fetal deaths and elective terminations increased the number of affected pregnancies by 58.7% for trisomy 13 and 72.2% for trisomy 18. Prenatal cytogenetic testing was reported in 70.8% of trisomy 13 cases and 76.1% of trisomy 18 cases. Among those with prenatal cytogenetic tests, 60.8% of trisomy 13 and 59.7% of trisomy 18 cases were electively terminated. Compared with non-Hispanic whites, non-Hispanic black race was associated with a decreased frequency of prenatal cytogenetic testing for both trisomy 13 and trisomy 18 (OR 0.24, 95% CI: 0.08-0.78 and OR 0.32, 95% CI: 0.14-0.69, respectively). The reported rates of prenatal cytogenetic testing remained stable throughout the period. As expected, maternal age > or =35 years was a risk factor for both conditions. However, while 67.1% (n = 55) of the trisomy 18 case mothers were > or =35 years, only 46.9% (n = 15) of the trisomy 13 case mothers were > or =35 years. Among live-born infants, the sex ratio among trisomy 18 infants showed an increased proportion of females: 60.4% female versus 39.6% male. However, the proportion was 48.3% female and 51.7% male among fetuses that were electively terminated in the second trimester. Inclusion of pregnancies that are prenatally diagnosed is critical for accurate surveillance and population-based analyses of these conditions.     

Origin and clinical relevance of chromosomal aberrations other than the common trisomies detected by genome-wide NIPS: results of the TRIDENT study

PurposeNoninvasive prenatal screening (NIPS) using cell-free DNA in maternal blood is highly sensitive for detecting fetal trisomies 21, 18, and 13. Using a genome-wide approach, other chromosome anomalies can also be detected. We report on the origin, frequency, and clinical significance of these other chromosome aberrations found in pregnancies at risk for trisomy 21, 18, or 13.MethodsWhole-genome shallow massively parallel sequencing was used and all autosomes were analyzed.ResultsIn 78 of 2,527 cases (3.1%) NIPS was indicative of trisomy 21, 18, or 13, and in 41 (1.6%) of other chromosome aberrations. The latter were of fetal (n = 10), placental (n = 22), maternal (n = 1) or unknown (n = 7). One case lacked cytogenetic follow-up. Nine of the 10 fetal cases were associated with an abnormal phenotype. Thirteen of the 22 (59%) placental aberrations were associated with fetal congenital anomalies and/or poor fetal growth (<p10), which was severe (<p2.3) in six cases.ConclusionGenome-wide NIPS in pregnancies at risk for trisomy 21, 18, or 13, reveals a chromosomal aberration other than trisomy 21, 18 or 13 in about one-third of the abnormal cases. The majority involves a fetal or placental chromosome aberration with clinical relevance for pregnancy management.     

应用无创性产前诊断技术诊断染色体数目异常及临床分析

目的通过分析12例应用无创性产前诊断技术诊断染色体数目异常病例,探讨该技术进行产前诊断的应用前景。方法12例患者于孕16W左右抽孕妇静脉血,分别分离血清和血浆。血清在本实验室进行三联血清学产前筛查。4m1血浆送深圳华大基因有限公司,应用二代测序技术进行测序分析;于孕18w左右均抽取羊水20ml进行羊水细胞培养和染色体核型分析。结果上述标本孕中期三联血清学筛查提示18-三体高风险2例、21-三体高风险10例,其中年龄高风险6例;应用无创性产前诊断技术诊断21-三体10例,18-三体2例;染色体核型分析21-三体10例,18-三体2例。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。     

无创性产前基因测序技术在染色体非整倍体中的应用

目的探讨高通量并行测序技术在胎儿染色体非整倍体检测中的应用价值。方法2012年10月至2013年4月,生化血清学筛查唐氏高危或高龄孕妇,采用高通量测序技术对胎儿染色体非整倍体进行无创性产前检测,评估患病风险率,提示高危孕妇进行核型分析确诊。结果813例无创检测高危孕妇,13例提示异常高危,异常率为1．59％,其中4例21三体,3例18三体,6例性染色体。核型确诊4例均为21三体,准确度100％;2例18三体;1例47,XXY和1例47,XXX。结论基于高通量测序技术的方法能快速、准确、无创检测唐氏综合征,相对18三体和性染色体检测准确度和稳定性有待优化与提高。     

Trisomy 18 and 21 in two siblings

While a child with trisomy 21 is a generally accepted indication for amniocentesis in succeeding pregnancies, the need for this prenatal test following a child with trisomy 18 is less certain. Although the likelihood of two successive pregnancies resulting in trisomies (18 and 21) appears to be small, it may be more common than is generally realized due to the high mortality of trisomy 18 prior to diagnostic studies.     

妊娠中晚期羊水细胞胎儿染色体异常核型分析

目的:分析妊娠中、晚期胎儿羊水染色体核型,了解该时期异常核型出现的频率类型及与诊断指征的关系。方法:357例有产前诊断指征的孕妇,在妊娠13-17行羊膜腔穿刺术,取羊水细胞培养,分析胎儿染色体核型。结果:羊水细胞培养成功率91.6%,发现异常核型21例(6.4%),其中妊娠中期检出异常5.7%(16/282);晚期异常11.1%(5/45),P>0.05。染色体异常携带者和各种三体为主要的异常核型,分别占52.4%(11/21)和33.3%(7/21)。高龄孕妇异常检出率为10.2%(5/49),非高龄组为5.8%(16/278),P>0.05。平衡易位组为52.4%,(11/21);胎儿宫内发育迟缓(IUGR)16.7%(1/6)血清学筛查风险值增高为5.9%(1/17)。结论:在有产前诊断为指征的孕妇,胎儿染色体异率为6.4%,染色体异常携带者和各种三体为主要的异常,是高龄以及IUGR最常见的异常。羊水细胞培养对于中、晚期妊娠的高风险孕妇行产前诊断是安全、可靠、诊断方法之一。     

唐氏综合征血清学筛查联合无创基因检测技术的临床研究

目的探讨唐氏综合征血清学筛查联合无创基因检测技术在增加唐氏综合征的检出率,降低假阳性率的意义。方法应用时间分辨荧光免疫分析技术,对11 748例孕妇进行血清标志物（PAPP-A/freeβ-h CG或者AFP/freeβ-h CG/u E3）联合筛查,使用Multical软件筛查高风险对象,血清学高风险孕妇抽取静脉血10ml,提取游离DNA,采用新一代高通量测序技术,结合生物信息分析,得出胎儿唐氏综合征的风险率。结果共筛查出高风险孕妇1024例,其中21三体高风险891例,18三体高风险133例,无创基因检测21三体高风险13例,18三体高风险4例,16例高风险孕妇经介入性产前诊断细胞培养均确诊为染色体异常,1例高风险孕妇染色体核型正常。结论无创基因检测在临床工作中可以改善血清学筛查结局,可以在临床工作中建立一套快速无创性产前诊断的有效模式。     

Systematic evidence-based review: The application of noninvasive prenatal screening using cell-free DNA in general-risk pregnancies

PurposeNoninvasive prenatal screening (NIPS) using cell-free DNA has been assimilated into prenatal care. Prior studies examined clinical validity and technical performance in high-risk populations. This systematic evidence review evaluates NIPS performance in a general-risk population.MethodsMedline (PubMed) and Embase were used to identify studies examining detection of Down syndrome (T21), trisomy 18 (T18), trisomy 13 (T13), sex chromosome aneuploidies, rare autosomal trisomies, copy number variants, and maternal conditions, as well as studies assessing the psychological impact of NIPS and the rate of subsequent diagnostic testing. Random-effects meta-analyses were used to calculate pooled estimates of NIPS performance (P < .05). Heterogeneity was investigated through subgroup analyses. Risk of bias was assessed.ResultsA total of 87 studies met inclusion criteria. Diagnostic odds ratios were significant (P < .0001) for T21, T18, and T13 for singleton and twin pregnancies. NIPS was accurate (≥99.78%) in detecting sex chromosome aneuploidies. Performance for rare autosomal trisomies and copy number variants was variable. Use of NIPS reduced diagnostic tests by 31% to 79%. Conclusions regarding psychosocial outcomes could not be drawn owing to lack of data. Identification of maternal conditions was rare.ConclusionNIPS is a highly accurate screening method for T21, T18, and T13 in both singleton and twin pregnancies.     

5933例孕中期母血清产前筛查回顾性分析与诊断

目的探讨孕中期母血清三联筛查法的临床意义及了解枣庄地区21-三体综合征（唐氏综合症）、18-三体综合征及NTD（神经管畸形）的发病率,旨在促进枣庄市产前筛查工作的更好开展。方法采用时间分辨荧光免疫分析法（DELFIA）对枣庄市产前诊断中心自2012年10月至2013年10月采集的5933个标本进行三联法孕中期母血清产前筛查。结果5933例孕妇中446例高风险,总体高风险率是7.5%;其中21-三体综合征高风险324例,高风险率是5.5%;18-三体高风险101例,高风险率是1.7%;NTD高风险21例,高风险率是0.4%。在自愿以及知情基础上经遗传咨询后有164例高风险孕妇行产前诊断,共确诊8例,确诊率是4.8%,其中21三体综合征4例,NTD 2例,畸胎瘤1例,三X综合征1例。结论结果表明孕中期母血清三联筛查法对于预测胎儿染色体病具有重要临床价值,可有效降低新生儿出生缺陷的发生;扩大产筛覆盖率,对实施出生干预工程,提高出生人口素质有重大意义。     

Twenty-year trends in the prevalence of Down syndrome and other trisomies in Europe: impact of maternal age and prenatal screening

This study examines trends and geographical differences in total and live birth prevalence of trisomies 21, 18 and 13 with regard to increasing maternal age and prenatal diagnosis in Europe. Twenty-one population-based EUROCAT registries covering 6.1 million births between 1990 and 2009 participated. Trisomy cases included live births, fetal deaths from 20 weeks gestational age and terminations of pregnancy for fetal anomaly. We present correction to 20 weeks gestational age (ie, correcting early terminations for the probability of fetal survival to 20 weeks) to allow for artefactual screening-related differences in total prevalence. Poisson regression was used. The proportion of births in the population to mothers aged 35+ years in the participating registries increased from 13% in 1990 to 19% in 2009. Total prevalence per 10 000 births was 22.0 (95% CI 21.7–22.4) for trisomy 21, 5.0 (95% CI 4.8–5.1) for trisomy 18 and 2.0 (95% CI 1.9–2.2) for trisomy 13; live birth prevalence was 11.2 (95% CI 10.9–11.5) for trisomy 21, 1.04 (95% CI 0.96–1.12) for trisomy 18 and 0.48 (95% CI 0.43–0.54) for trisomy 13. There was an increase in total and total corrected prevalence of all three trisomies over time, mainly explained by increasing maternal age. Live birth prevalence remained stable over time. For trisomy 21, there was a three-fold variation in live birth prevalence between countries. The rise in maternal age has led to an increase in the number of trisomy-affected pregnancies in Europe. Live birth prevalence has remained stable overall. Differences in prenatal screening and termination between countries lead to wide variation in live birth prevalence.     

Triple marker screening for fetal chromosomal abnormalities in Korean women of advanced maternal age

The purpose of this article is to assess the value of maternal serum triple marker screening of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) for the prenatal diagnosis of fetal chromosomal abnormalities in Korean women of advanced maternal age. Maternal sera were collected from 458 pregnant Korean women aged 35 between 15 and 20 weeks gestation before amniocentesis. A patient- specific second trimester risk for fetal Down's syndrome was calculated using the median values for AFP, hCG, uE3 and maternal age. Twelve fetal chromosomal abnormalities were identified. These included six cases of trisomy 21, one case of 46,XY/47,XY,+21, two cases of trisomy 18, one case of trisomy 13, and two cases of 45, X. A cutoff level of 1:200 detected 85.7% (6/7) of the cases of Down's syndrome and 20% (1/5) of the other aneuploidies, with a 27.3% false positive rate. However, a cutoff level of 1:270 did not result in any gains in detecting Down's syndrome or other aneuploidies at the expense of a false positive rate of 34.3%. Second trimester triple marker testing is an effective screening tool for detecting fetal Down's syndrome in Korean women > or = 35 years old. However, it is not an effective screening tool for non-Down's chromosomal abnormalities.     

Chromosome findings in 2,500 second trimester amniocenteses

We have analyzed the chromosome abnormalities found in 2,500 amniocenteses for prenatal diagnosis; 1,887 (75%) were performed because the maternal age was 34 years or more. Chromosome abnormalities were detected in 1.80% of those referred for advanced maternal age, 1.2% between ages 34 and 39 years and 4.6% 40 years and over. Of these, four occurred in women who would have been 34 years at delivery (2.9%). Trisomy 21 accounted for 50% of the chromosome abnormalities; sex chromosome abnormalities, for 25%; the remaining 25% was divided equally between trisomy 18 and partial trisomies and mosaics. Unexpected translocations were found in 0.4%, of which two-thirds were balanced and identified in one parent. The accuracy was 99.6%.