通过NIPT的基因组方案来推动革新
不断发展的无创筛查选择，如无创产前检测（NIPT），可以提供染色体疾病的早期筛查，它只需一管血，早在怀孕10周时即可进行。
其他类型的产前筛查和诊断检测可能需要多次看医生、多次抽血，或假阳性的风险更高。产前诊断检测，如绒毛膜取样（CVS）或羊膜穿刺，可以给出大多数染色体疾病的明确结果，但存在流产的风险。
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登陆NIPT对母亲或婴儿的风险极小
NIPT分析血液样本中游离的胎儿和母体DNA，以筛查常见的染色体疾病，包括21三体（唐氏综合征）、18三体（Edwards综合征）和13三体（Patau综合征）。
NIPT对母亲或婴儿的风险极小，具有高的检测率和低的误报率。，美国妇产科医师学会（ACOG）和国际产前诊断协会（ISPD），以及其他的专业协会，都表示NIPT是适合所有孕妇的一个筛查选择。1,2
verifi Prenatal Test就是这样一种无创检测，可对21号、18号和13号染色体的非整倍体进行筛查。对于单胎妊娠，它可提供额外的性染色体和特定微缺失的筛查。在双胎妊娠中，它提供21号、18号和13号染色体的非整倍体筛查和Y染色体缺失的筛查。结果在收到样本3-5天内报告。取决于需求，报告时间可进行调整。
verifi的检测性能指标
verifi的检测性能指标对比。
点击下面的 ， 查看敏感性和特异性数据表
| CLIA实验室 | 验证研究* | |||
|---|---|---|---|---|
| 疾病 | 观察到的敏感性** (范围)*** | 观察到的特异性** (范围)*** | 敏感性 | 特异性 |
| 21三体 | 99.49% (98.66–99.53%) | 99.77% (98.92–99.91%) | 100% | 99.76% |
| 18三体 | 97.23% (94.20–98.15%) | 99.69% (99.51–99.85%) | 97.37% | 99.57% |
| 13三体 | 97.98% (95.56–98.87%) | 99.84% (99.77-99.93%) | 87.50% | 100% |
* Illumina。verifi Prenatal Test的分析验证：针对21、18和13三体的检测性能增强，且可选择对性染色体的状态进行分类。Illumina的白皮书。2012
** 观察到的敏感性和特异性是利用现有的结果数据计算的，其队列大小按照“已经过结果确诊的阳性病例的比例”而进行调整。
*** 范围的下限是基于假设所有未报告结果均为不一致结果，范围的上限则是基于假设所有未报告结果均为一致性结果而得出。
评估检测性能的指标
在患者进行非整倍体产前筛查之前和之后，检测性能指标都是必不可少的。
一项检测的敏感性和特异性可帮助您：
决定为患者提供哪些产前筛查选项
确定选择哪个实验室
将非整倍体筛查的好处和局限性告知患者（检测率和误报率）
点击下面的 查看敏感性和特异性的数据表。
| Condition | Sensitivity | 95% CI | Specificity | 95% CI |
|---|---|---|---|---|
| Trisomy 21 | 99.2% | 98.5-99.6% | 99.91% | 99.86–99.95% |
| Trisomy 18 | 96.3% | 94.3–97.9% | 99.87% | 99.80–99.93% |
| Trisomy 13 | 91.0% | 85.0–95.6% | 99.87% | 99.74–99.95% |
NIPT performance for trisomies 21, 18, and 13 in singleton pregnancies as reported in a large, independent meta-analysis3
Data from a meta-analysis of 37 published NIPT studies between January, 2011 and January, 2015. Sensitivity and specificity are test specific, not patient specific. As such, they are not expected to change significantly based on an individual patient’s clinical picture (eg. maternal age, ultrasound findings).
筛查之后的性能指标考虑
阳性预测值（PPV）
一项检测的PPV可以帮助您确定阳性结果有多大可能是真正的阳性。PPV是基于检测的敏感性和特异性以及待检测群体中疾病的发生率。
为什么发生率对PPV很重要
常染色体三体（如21三体）的发生率随着母亲年龄的增加而增加，故PPV也是如此。21三体是活产儿中最普遍的常染色体三体。因此，21三体的PPV比18三体和13三体更高，后两者没那么普遍。图中的PPV是根据年龄相关的发生率计算的；其他非整倍体风险因素的存在（如B超异常）有可能使PPV比图中显示的更高。
为什么特异性对PPV很重要
虽然年轻妇女的PPV较低，但NIPT的PPV将高于传统的血清筛查，因为NIPT有着明显更高的特异性（假阳性率更低）。5
Why Specificity Matters for PPVs
While PPVs are lower in younger women, PPVs for NIPT will be higher than those of traditional serum screening at all maternal ages because NIPT has significantly higher specificity (a lower false positive rate).8
Why Prevalence Matters for PPVs
Because the prevalence of autosomal trisomies (eg, trisomy 21) increases with maternal age, so do the PPVs. Trisomy 21 is the most prevalent autosomal trisomy in live births. Thus, the PPVs are higher for trisomy 21 than for trisomies 18 and 13,
which are less common. The PPVs below are calculated based on age-related prevalence; the presence of other aneuploidy risk factors (e.g. ultrasound abnormalities) would likely increase the PPVs over those shown here.
Illumina的与众不同之处
Illumina致力于为实验室和临床医疗合作伙伴提供全面的解决方案和检测方案，以改善人类健康。已发表的数据表明，与靶向方法相比，使用全基因组测序（WGS）的NGS是NIPT的首选技术。
鉴于这些研究中超过99.7%的NIPT样本使用了Illumina的NGS技术，我们正在帮助推动产前筛查的突破。因此，市场上无创产前检测中失败率最低的verifi Prenatal Test才成为患者的最佳选择。
点击下面的 查看样本运行数据表。
| Test (Company) | Current technology platform | Platform provider | Number of published samples | ||
|---|---|---|---|---|---|
| Illumina NGS | Ion Proton NGS | Affymetrix array | |||
| Bambni Test (Berry Genomics) | NGS | Illumina | 3,268 | 0 | 0 |
| MaterniT21 PLUS Test (Sequenom) | NGS | Illumina | 293,243 | 0 | 0 |
| NIFTY Test (BGI) | NGS | Illumina | 168,655 | 0 | 0 |
| Panorama Prenatal Screen (Natera) | NGS | Illumina | 55,077 | 0 | 0 |
| PrenaTest (LifeCodexx AG) | NGS | Illumina | 504 | 0 | 0 |
| verifi Prenatal Test (Illumina) | NGS | Illumina | 113,561 | 0 | 0 |
| IONA Test (Premaltha) | NGS | Ion Proton | 0 | 684 | 0 |
| Harmony Prenatal Test (Arlosa)* | Array | Affymetrix | 44,313 | 0 | 1,677 |
| Total | 678,621 | 684 | 1,677 | ||
A PubMed search for "cell-free, DNA, prenatal," "noninvasive prenatal testing," and "noninvasive prenatal screening" was performed on November 30, 2015. All validation and clinical studies using unique samples were included, where a current clinical NIPT provider performed sample analysis. Case studies and studies published in a language other than English were excluded. A total of 59 published studies were surveyed. Data calculations on file. Illumina, Inc. 2015. NGS = next-generation sequencing; either whole-genome or targeted.
*In 2014, Ariosa switched from sequencing to arrays for clinical samples despite limited published data on this platform.
Test Failures May Lead to Invasive Procedures.†
Theoretical example of the number of invasive procedures requested due to NIPT failure and false positive rates of the assays. Failure rates include assay failures and samples rejected due to low fetal fraction. Assay failure rate for the Harmony test is based on NGS studies and may not be consistent with actual test results achieved using the array-based Harmony Test currently in use.12-18
†Affected pregnancies with a screening test failure were excluded from the number of detected T21.
资料
- Committee Opinion No. 640: Cell-free DNA Screening for Fetal Aneuploidy. Obstet Gynecol. 2015;126(3):e31-37.
- Benn P, Borrell A, Chiu RWK, et al. Position statement from the Chromosome Abnormality Screening Committee on behalf of the Board of the International Society for Prenatal Diagnosis. Prenat Diagn. 2015;35(8):725-734.
- Gil MM, Quezada MS, Revello R, Akolekar R, Nicolaides KH. Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: updated meta-analysis. Ultrasound Obstet Gynecol. 2015;45(3):249-266.
- Gardner RJM, Sutherland GR, Shaffer LG. Parental age counseling and screening for fetal trisomy. Chromosome abnormalities and genetic counseling. 4 ed: Oxford University Press; 2012:403-416.
- Benn P, Curnow KJ, Chapman S, Michalopoulos SN, Hornberger J, Rabinowitz M. An Economic Analysis of Cell-Free DNA Non-Invasive Prenatal Testing in the US General Pregnancy Population. PLoS One. 2015;10(7):e0132313.
- Wellesley D, Dolk H, Boyd PA, et al. Rare chromosome abnormalities, prevalence and prenatal diagnosis rates from population-based congenital anomaly registers in Europe. Eur J Hum Genet. 2012;20(5):521-526.
- Bianchi DW, Parker RL, Wentworth J, et al. DNA sequencing versus standard prenatal aneuploidy screening. N Engl J Med. 2014;370(9):799-808.
- Malone FD, Canick JA, Ball RH, et al. First-trimester or second-trimester screening, or both, for Down's syndrome. N Engl J Med. 2005;353(19):2001-2011
- Committee Opinion No. 640: Cell-free DNA Screening for Fetal Aneuploidy. Obstet Gynecol. 2015;126(3):e31-37.
- Practice Bulletin No. 163: Screening for Fetal Aneuploidy. Obstet Gynecol. 2016;127(5):979-981.
- The American Congress of Obstetricians and Gynecologists. NIPT Cell Free DNA Screening Predictive Value Calculator. National Society of Genetic Counselors (NSGC) and Perinatal Quality Foundation (PQF). Endorsed December 2015. 2015; http://www.acog.org/Resources-And-Publications/Endorsed-Documents. Accessed January 28, 2015.
- Taneja PA, Snyder HL, de Feo E, et al. Noninvasive prenatal testing in the general obstetric population: clinical performance and counseling considerations in over 85 000 cases. Prenat Diagn. 2016: 36(3): 237-43.
- McCullough RM, Almasri EA, Guan X, et al. Non-invasive prenatal chromosomal aneuploidy testing—clinical experience: 100,000 clinical samples. PLoS One. 2014: 9(10):e109173.
- Norton ME, Jacobsson B, Swamy GK, et al. Cell-free DNA analysis for noninvasive examination of trisomy. N Engl J Med. 2015: 372(17): 1589-97.
- Dar P, Curnow KJ, Gross SJ, et al. Clinical experience and follow-up with large scale single-nucleotide polymorphism-based noninvasive prenatal aneuploidy testing. Am J Obstet Gynecol. 2014: 211(5): 527.e1-527.e17.
- Pergament E, Cuckle H, Zimmermann B, et al. Single-nucleotide polymorphism-based noninvasive prenatal screening in a high-risk and low-risk cohort. Obstet Gynecol. 2014;124(2 Pt 1):210-218.
- Nicolaides KH. Screening for fetal aneuploidies at 11 to 13 weeks. Prenat Diagn. 2011;31(1):7-15.
- Wald NJ, Rodeck C, Hackshaw AK, et al. SURUSS in perspective. Semin Perinatol. 2005;29(4):225-235.
verifi Prenatal Test（verifi 产前检测）是由Illumina的全资子公司Verinata Health公司开发的，其性能特点由该公司确定。VHI的实验室经过CAP认证和临床实验室改进修正案（CLIA）认证，具有开展高度复杂的临床实验室检测的资格。它尚未经过美国食品和药物管理局的批准和认证。