高通量测序胎儿染色体非整倍体筛查方法在双胎妊娠中的应用

目的探讨高通量测序用于胎儿染色体异常产前筛查在双胎妊娠胎儿非整倍体染色体异常产前检测中的应用价值。方法选择妊娠15~18周接受孕中期血清学筛查和核型分析的200例双胎孕妇,妊娠12~27周行非侵入产前诊断(NIPT),对于染色体异常风险度升高者行双胎妊娠羊膜腔穿刺染色体核型分析;未提示风险度升高者,分娩时留取脐血检查有无染色体异常;双胎妊娠出现流产等不良妊娠结局者,留取胎儿组织提取DNA等进行高通量测序及染色体核型分析。以胎儿/新生儿染色体核型分析结果为金标准,分析NIPT结果。结果200例双胎妊娠患者,行孕中期血清学筛查155例(77.5%,155/200),45例(22.5%,50/200)因年龄高风险未行血清学筛查。155例血清学筛查中,高风险孕妇13例(8.4%,13/155),核型分析和妊娠结局均未发现异常。200例NIPT显示,1例性染色体异常(0.5%,1/200),染色体核型分析证实双胎之一胎儿核型为45,XO;1例18-三体综合征高风险(0.5%,1/200),双胎核型未见明显异常;1例21-三体高风险(0.5%,1/200),双胎之一核型为47,+21,XN;余197例染色体核型分析未提示明显异常。结论高通量测序胎儿染色体异常产前筛查在双胎胎儿染色体非整倍体的检测有一定的应用价值。     

妊娠早期胎儿颈部透明层厚度与胎儿预后的前瞻性队列研究

目的探讨妊娠早期胎儿颈部透明层(NT)厚度与胎儿预后的关系。方法收集2015年12月至2018年12月于南京大学医学院附属鼓楼医院行妊娠早期胎儿NT厚度测量的单胎孕妇,共4958例建立前瞻性研究队列,进行妊娠早期胎儿结构超声筛查、妊娠早期血清学筛查、妊娠中期超声筛查及对新生儿出生后28 d的体格检查。根据妊娠早期超声筛查的结果,分为胎儿NT增厚(≥3.0 mm)者167例与NT厚度正常者4791例;将胎儿NT增厚的孕妇,分为胎儿单纯NT增厚者86例与NT增厚合并结构异常者81例。分析不同NT厚度胎儿的预后,并重点对单纯NT增厚与NT增厚合并结构异常胎儿的妊娠结局进行分析。妊娠早期超声筛查发现胎儿结构异常或血清学筛查结果为高风险的孕妇,经绒毛穿刺取样术行染色体微阵列分析(CMA)检测以明确产前诊断。结果(1)胎儿NT厚度正常孕妇的妊娠结局:共4791例孕妇,包括胎儿NT厚度正常且无结构异常者4726例,其中妊娠中期及产后新诊断结构异常83例,4688例活产;胎儿NT厚度正常但结构异常的孕妇65例,其中61例孕妇终止妊娠,4例活产。(2)胎儿单纯NT增厚孕妇的妊娠结局:86例孕妇中,66例(76.7%,66/86)行CMA检测,3例胎儿诊断为21三体综合征;除7例孕妇选择终止妊娠外,余79例行妊娠中期超声检查、新生儿出生后28 d体格检查、新生儿电话随访至6~21个月均未发现发育异常。(3)胎儿NT增厚合并结构异常孕妇的妊娠结局:81例孕妇中,73例(90.1%,73/81)行CMA检测,其中32例的胎儿为染色体非整倍体异常。70例选择终止妊娠,2例妊娠中期自然流产,9例活产。(4)NT增厚是否合并结构异常胎儿的产前诊断结果及预后比较:单纯NT增厚的胎儿染色体非整倍体的发生率为3.5%(3/86),合并结构异常者为39.5%(32/81),两者比较,差异有统计学意义(χ2=32.7,P<0.01);胎儿单纯NT增厚孕妇的健康新生儿存活率为91.9%(79/86),合并结构异常者为9.9%(8/81),两者比较,差异有统计学意义(χ2=112.3,P<0.01)。结论妊娠早期,超声筛查胎儿NT及结构,能提高出生缺陷的产前筛查率。单纯NT增厚胎儿的染色体非整倍体的发生率较低,新生儿健康存活率较高。     

无创产前检测在胎儿染色体非整倍体筛查中的应用

<正>胎儿染色体非整倍体异常可导致严重的不良妊娠结局及出生缺陷,其产前筛查及诊断是出生缺陷二级预防的重要内容之一。常见严重或致死的胎儿染色体非整倍体有21-三体(唐氏综合征,Down′s Syndrome)、18-三体(爱德华氏综合征,Edwards Syndrome)和13-三体(帕陶氏综合征,Patau Syndrome),其中以21-三体最常见,发病率为0.7‰～1.5‰^[1]。     

双胎妊娠染色体异常的产前筛查及产前诊断

双胎妊娠发生胎儿畸形、染色体异常的风险较单胎妊娠高。近年来双胎妊娠发生率和高龄产妇数量不断增加,双胎妊娠的早期筛查以及产前诊断十分重要。早孕期,颈项透明层(nuchal translucency,NT)超声筛查是重要手段,不建议单独使用血清学筛查;中孕期超声结构筛查对检出胎儿结构异常有一定意义。无创产前基因检测技术的发展,对降低侵入性产前诊断的风险有重要意义,但由于目前临床证据尚不充分,双胎妊娠行无创基因检测仍需谨慎。     

无创产前检测技术在双胎染色体非整倍体疾病筛查中应用研究

目的探讨无创产前检测技术在双胎染色体非整倍体疾病筛查中的临床应用价值。方法对2015年10月1日至2016年8月1日在中国医科大学附属盛京医院就诊,自愿接受无创产前检测的423例妊娠12~31周双胎孕妇,抽取外周血获取胎儿游离DNA,应用高通量测序技术检测胎儿非整倍体的情况。无创检测的结果由羊水细胞及分娩时脐血核型分析进行验证。结果无创产前检测异常者8例,4例提示21-三体高风险,2例提示18-三体高风险,2例提示X染色体单体(45,X)。6例三体高风险胎儿经羊水或脐血穿刺检查结果确认无误。1例X染色体单体的羊水结果与检测结果一致,另1例羊水检测结果正常,但随后确认该孕妇核型为46,XX[36]/45,X[64]。经验证的低风险者176例,均与其一致。结论无创产前检测作为一种快速、安全的产前筛查手段,在双胎的非整倍体疾病筛查中有较高的灵敏度和特异度,具有临床应用价值。     

产前筛查——从血清学筛查到无创产前检测

        产前筛查一般指的是对胎儿常见染色体非整倍体的筛查,即21-三体综合征、18-三体综合征、13-三体综合征,不包括其他染色体非整倍体。 浏览更多请关注本刊微信公众号及当期杂志。     

双胎妊娠的产前筛查、诊断与干预：转诊是关键

双胎妊娠产前筛查和诊断具有极强的专业性和复杂性,颈项透明层（NT）厚度联合外周血游离DNA［无创产前检测（NIPT）］检测可提高非整倍体筛查的检出率,减少不必要的介入性产前诊断。双胎之一胎儿异常后的宫内干预需建立在精准的产前诊断基础之上。双胎妊娠的特殊并发症的诊治应转至专业的产前诊断中心或区域性的胎儿医学中心进行。     

21-三体综合征妊娠早期联合筛查模式的评估

目的：评估妊娠早期联合筛查21-三体综合征模式的质量。方法：入选者为500例妊娠11～13＋6周进行产前筛查的妊娠妇女,超声检测胎儿颈项透明层（nuchal translucency,NT）厚度,同时取妊娠妇女静脉血,以时间分辨法检测血清中游离人绒毛膜促性腺激素亚单位（β-hCG）及妊娠相关蛋白A（PAPP-A）水平,并根据患者年龄、体质量、种族、吸烟史、妊娠方式、妊娠周数等转化成该指标的中位数倍数（MoM）,风险值为1∶270,联合评估妊娠妇女21-三体综合征的患病风险,记录实施产前诊断妊娠妇女胎儿的染色体核型。所有妊娠妇女均进行妊娠期监测及产后随访,将妊娠妇女及胎儿结局输入数据库。最后对妊娠早期时的筛查模式及筛查质量进行评估。结果：①500例中有6例为21-三体高风险（行产前诊断5例）,其中3例在产前诊断时确诊。另有40例为年龄高风险（＞35岁）,其中5例行产前诊断,均为正常核型胎儿。②在妊娠早期,非21-三体核型胎儿的NT厚度随其顶臀长（CRL）增加而增加。③正常胎儿母亲血清PAPP-A水平随妊娠周增加而增加,β-hCG水平随妊娠周增加而下降。结论：①单独年龄高风险不应作为产前诊断的指标。②NT厚度与妊娠周相关,应进行多中心大样本研究,并根据不同妊娠周建立适合中国人群的NT诊断标准。③妊娠早期筛查应在有超声NT测量资质的医院进行,且最好在妊娠12周时进行。④妊娠早期母亲血清PAPP-A及β-hCG水平变化与妊娠周有关。     

双胎妊娠产前筛查和产前诊断

双胎妊娠的产前筛查和产前诊断与单胎比较其准确性差,咨询难度大。双胎妊娠的绒毛膜性诊断是双胎妊娠产前筛查的关键基础,目前不推荐对于双胎妊娠进行唐氏综合征的血清学筛查,而需要重视双胎妊娠早孕期的超声软指标筛查以及其他的结构筛查。无创产前筛查的方法对双胎妊娠有一定的筛查意义。高危孕妇采取介入性诊断技术进行染色体异常的检查时,对于单卵双胎妊娠建议进行1个胎儿的采样,而双卵双胎则需要分别采样,如为胎儿结构异常则无论其绒毛膜性均需要进行分别采样。双胎妊娠的介入性诊断流产率略高于单胎妊娠,手术前需要对孕妇及家属充分地知情告知。     

胎儿颈项透明层增厚与染色体异常的关系

目的 通过超声测量胎儿颈项透明层厚度(NT),探讨NT增厚与胎儿染色体异常的关系。 方法 选择2007年2月至2009年12月在北京大学人民医院产前检查的孕10~22周经腹超声检查胎儿NT增厚的孕妇78例,行羊水或脐带血穿刺进行胎儿染色体核型分析,并进行超声及分娩结局的随访。 结果 78例NT增厚病例中,染色体异常3例,均为21-三体综合征,发生率为3.85%(3/78)。6例发生不良妊娠结局,其中5例伴胎儿异常,胎儿异常分别为右侧脑积水和脑脊膜膨出、多囊肾、心脏畸形、风疹病毒感染和全身水肿。 结论 NT增厚对染色体异常特别是21-三体综合征的早期筛查具有重要意义,是孕早中期产前超声筛查的主要指征之一。     

双胎妊娠非整倍体异常的产前筛查与产前诊断

双胎妊娠非整倍体产前筛查较单胎复杂。应在早孕期确定孕周、绒毛膜性并测量颈项透明层厚度。早孕期联合筛查优于中孕期血清学筛查,但检出率明显低于单胎妊娠。无创产前检查用于双胎筛查仍需更多研究数据。双胎之一胚胎停育将影响早孕期筛查的准确性。产前诊断时区分标记双胎是需要注意的重要问题。     

Combined measurement of fetal nuchal translucency, maternal serum free beta-hCG, and pregnancy-associated plasma protein A for first-trimester Down's syndrome screening.

PURPOSE: It has been proposed that first-trimester Down's syndrome screening has a higher detection rate compared to second-trimester biochemical screening. This study investigated the accuracy of Down's syndrome screening during gestational weeks 10 to 13 using the combination of fetal nuchal translucency (NT) measurement with maternal serum concentrations of free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A). METHODS: A total of 1,514 women with singleton pregnancies were enrolled in this study. Fetal NT was measured using the criteria published by the Fetal Medicine Foundation. Maternal serum concentrations of free beta-hCG and PAPP-A were determined by microtiter-plate ELISA. Down's syndrome risk was calculated using multivariate Gaussian distribution and Alpha software. RESULTS: Seventeen (1.12%) of the 1514 screened pregnancies had a fetal NT of at least 3 mm, and 41.2% of these had a poor pregnancy outcome, including four fetal aneuploidies. The odds of a fetal aneuploidy when the NT was greater than 2.0 multiples of median (MoM) was 90, when serum PAPP-A concentration was less than 0.45 MoM, it was 8.6, and when serum free beta-hCG concentration was greater than 2.2 MoM, it was 4.7. Using a risk cut-off level of 1 in 400, nine of 10 fetal aneuploidies were identified with a 4.7% false-positive rate, including two with trisomy 21, one with trisomy 18, and three with Turner's syndrome. CONCLUSIONS: This study demonstrated that Down's syndrome screening using the combined test in the first trimester had a higher detection rate than that of serum screening in the second trimester. Implementation of NT measurement in the first trimester provides substantial advantages for Down's syndrome detection and early diagnosis of fetal structural abnormalities.     

Prenatal Screening for and Diagnosis of Aneuploidy in Twin Pregnancies

ObjectiveTo provide a Canadian consensus document with recommendations on prenatal screening for and diagnosis of fetal aneuploidy (e.g., Down syndrome and trisomy 18) in twin pregnancies.OptionsThe process of prenatal screening and diagnosis in twin pregnancies is complex. This document reviews the options available to pregnant women and the challenges specific to screening and diagnosis in a twin pregnancyOutcomesClinicians will be better informed about the accuracy of different screening options in twin pregnancies and about techniques of invasive prenatal diagnosis in twins.EvidencePubMed and Cochrane Database were searched for relevant English and French language articles published between 1985 and 2010, using appropriate controlled vocabulary and key words (aneuploidy, Down syndrome, trisomy, prenatal screening, genetic health risk, genetic health surveillance, prenatal diagnosis, twin gestation). Results were restricted to systematic reviews, randomized controlled trials, and relevant observational studies. Searches were updated on a regular basis and incorporated in the guideline to August 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies The previous Society of Obstetricians and Gynaecologists of Canada guidelines regarding prenatal screening were also reviewed in developing this clinical practice guideline.ValuesThe quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1).Benefits, harms, and costsThere is a need for specific guidelines for prenatal screening and diagnosis in twins These guidelines should assist health care providers in the approach to this aspect of prenatal care of women with twin pregnancies.Summary StatementsFetal nuchal translucency combined with maternal age is an acceptable first trimester screening test for aneuploidies in twin pregnancies. (II-2)First trimester serum screening combined with nuchal translucency may be considered in twin pregnancies It provides some improvement over the performance of screening by nuchal translucency and maternal age by decreasing the false-positive rate. (II-3)Integrated screening with nuchal translucency plus first and second trimester serum screening is an option in twin pregnancies. Further prospective studies are required in this area, since it has not been validated in prospective studies in twins (III)Non-directive counselling is essential when invasive testing is offered (III)When chorionic villus sampling is performed in non-monochorionic multiple pregnancies, a combination of transabdominal and transcervical approaches or a transabdominal only approach appears to provide the best results to minimize the likelihood of sampling errors. (II-2)RecommendationsAll pregnant women in Canada, regardless of age, should be offered, through an informed counselling process, the option of a prenatal screening test for the most common clinically significant fetal aneuploidies. In addition, they should be offered a second trimester ultrasound for dating, assessment of fetal anatomy, and detection of multiples. (I-A)Counselling must be non-directive and must respect a woman's right to accept or decline any or all of the testing or options offered at any point in the process. (III-A)When non-invasive prenatal screening for aneuploidy is available, maternal age alone should not be an indication for invasive prenatal diagnosis in a twin pregnancy. (II-2A) If non-invasive prenatal screening is not available, invasive prenatal diagnosis in twins should be offered to women aged 35 and over. (II-2B)Chorionicity has a major impact on the prenatal screening process and should be determined by ultrasound in the first trimester of all twin pregnancies (II-2A)     

早孕期胎儿鼻骨缺失与染色体异常关系的研究

目的:探讨早孕期胎儿鼻骨缺失与胎儿染色体异常之间的关系。方法:回顾性分析2016年1月至2017年12月广州医科大学附属第三医院产前诊断及胎儿医学中心和福建医科大学附属第一医院超声影像科早孕期超声检查提示胎儿鼻骨缺失的相关资料,分析胎儿单纯鼻骨缺失及其在合并其他超声异常时对诊断染色体异常的价值。结果:高龄孕妇的胎儿单纯鼻骨缺失及合并其他超声异常时胎儿染色体异常的发生率分别为6.78%和75.00%,同非高龄孕妇的胎儿染色体异常率(分别为0.80%和42.50%)比较,差异均有统计学意义(P<0.05)。胎儿单纯鼻骨缺失的染色体异常率为2.72%,当合并其他异常指标时,胎儿染色体异常率升至58.75%,差异有统计学意义(P<0.01)。胎儿鼻骨缺失在合并颈项透明层(NT)增厚时,胎儿染色体异常的总发生率为60.81%。当NT>3.5 mm时胎儿染色体异常率达77.78%,与NT≤3.5 mm时的染色体异常发生率(34.48%)比较,差异有统计学意义(P<0.05)。结论:早孕期超声检查提示胎儿鼻骨缺失时,需详细的胎儿超声结构筛查评估,当发现合并其他超声异常时,临床医师应向孕妇提供遗传咨询,建议行产前诊断以排除胎儿染色体异常。     

Screening and diagnosis of chromosomal abnormalities in twin pregnancy

Twin pregnancies are at an increased risk of adverse pregnancy and perinatal outcome as compared to singleton gestations, mainly as the consequence of the higher rate of preterm birth, chromosomal as well as structural anomalies, placental abnormalities, and complications unique to monochorionic placentation.Screening for chromosomal anomalies poses diagnostic and management challenges when applied to twin pregnancies. The recent implementation of cell-free fetal DNA (cffDNA) in clinical practice raises the questions whether a more accurate test should be offered to twin pregnancies in view of the higher false positive rate of traditional screening and the higher risk of fetal loss following amniocentesis or chorionic villus sampling (CVS) in multiple gestations. Finally, twin pregnancies require a tailored approach for aneuploidy screening, such as nuchal translucency (NT) or crown rump length discordance, discordant fetal anomalies, or monoamniotic gestations.The present review aims to provide an up-to-date critical appraisal of screening and prenatal diagnosis of chromosomal abnormalities in twin pregnancies.     

Second trimester ultrasound screening for chromosomal abnormalities

The use of prenatal ultrasound has proven efficacious for the prenatal diagnosis of chromosomal abnormalities. The first sonographic sign of Down syndrome, the thickened nuchal fold, was first described in 1985. Since that time, multiple sonographically-identified markers have been described as associated with Down syndrome. The genetic sonogram, involving a detailed search for sonographic signs of aneuploidy, can be used to both identify fetuses at high risk for aneuploidy and, when normal, can be used to decrease the risk for aneuploidy for a pregnancy when no sonographic markers are identified. Combining the genetic sonogram with maternal serum screening may be the best method of assessing aneuploidy risk for women who desire such an assessment in the second trimester. Trisomy 18, Trisomy 13, and triploidy are typically associated with sonographically identified abnormalities and have a high prenatal detection rate. The use of the described sonographic signs in low-risk women requires further investigation, however, patients at increased risk for aneuploidy due to advanced maternal age or abnormal serum screening can benefit from a genetic sonogram screening for sonographic signs of aneuploidy to adjust their baseline risk of an affected fetus.     

Patient and health professional acceptance of integrated serum screening for Down syndrome

Integrated testing for Down syndrome combines first trimester maternal serum and nuchal translucency (NT) measurements with second trimester maternal serum measurements into a single second trimester Down syndrome risk. A variant of integrated testing, the integrated serum test, requires only the serum measurements and may be more suitable for widespread use in the general pregnancy population. Concern has been voiced that women will find the delay associated with waiting for screening results unacceptable for either fully integrated (including NT measurements) or integrated serum testing. To address this issue, we surveyed 60 women from a population of 8773 women enrolled in an integrated serum screening intervention trial in Maine. The women all had also undergone traditional second trimester screening 1 to 2 years earlier. All 60 women remembered having the integrated serum test, and 59 remembered having a prenatal test in their previous pregnancy. Three-quarters of women did not experience anxiety relating to the wait for final results in the second trimester, and 95% would consider being screened by the integrated serum test in a future pregnancy. Women receiving prenatal care at the primary care level are prepared to wait until the second trimester for more accurate Down syndrome risk estimates on which to base their decision-making.     

From Down syndrome screening to noninvasive prenatal testing: 20 years' experience in Taiwan

Down syndrome is the most common autosomal chromosome aneuploidy. The prenatal Down syndrome screening protocol has been known in Taiwan for the past 20 years. The maternal serum double markers required for the screening test was first implemented into the general prenatal check-up back in 1994, where it had around a 60% detection rate at a 5% false positive rate. The first trimester combined test was started in 2005, and the maternal serum quadruple test was introduced in 2008 to replace the previous double test. The overall detection rate for the current screening strategies (first trimester combined or second trimester quadruple test) in Taiwan ranges between 80% and 85% at a fixed 5% false positive rate. Noninvasive prenatal testing (NIPT) is the latest powerful fetal aneuploidy detection method and has become commercially available in Taiwan starting from 2013. The sensitivity and specificity for NIPT are very high (both over 99%) according to large worldwide studies. Our preliminary data for NIPT from 11 medical centers in Taiwan have also shown a 100% detection rate for Down syndrome and Edwards syndrome, respectively. Invasive chromosome studies such as amniocentesis or chorionic villus sampling cannot be replaced by NIPT, and all prenatal screening and NIPT results require confirmation using invasive testing. This review discusses the Down syndrome screening method assessments and the progress of NIPT in Taiwan.