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NIPT Non-Invasive Prenatal Test By Dr. A. Kollaee (DCLS & PhD in Medical Genetics)
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What are the goals of NIPT?
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Should NIPS be offered to all pregnant patients? ACMG recommends: - Informing all pregnant women that NIPS is the most sensitive and reliable option for traditionally screened aneuploidies involving chromosomes 13,18 and 21
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Cell-Free DNA (cfDNA) Small Fragments (<200 bp) of DNA In Maternal Circulation Maternal Fraction Adipocytes White Blood Cells Fetal Fraction Placental Cells (Trophoblasts) in Maternal Circulation 10- 15% of Total cfDNA in Maternal Plasma, After 10 Wks of Gestation Which One: cffDNA or cfDNA? AJOG 2015; SMFM Publiation Committee
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Available commercial NIPT testing Europe -Prena test -Life Codexx -IONA test -Premaitha Health China - NIFTY Test – BGI USA - Harmony Test - Ariosa Diagnostic, Sanjose California - MaterniT21 Plus Test – Sequenom Laboratories, San Diego - Verifi Test – Verinata Health - Panorama Test – Natera San Carlos California
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Differentiating NIPT Methodologies
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Trisomy Detection by Counting Fetal Disomy Fetal Trisomy Maternal “Fetal Fraction of cfDNA Is Key In “Counting” => Higher Fetal Fractions => Easier to Detect Trisomy (Norton, Et Al. 2013) How Fetal Fraction Affects Sensitivity Just Visually Compare!
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Fetal Fraction Matters for Counting 0-4%4-8%8%+ Fetal Fraction Too Low To Report Intermediate Fetal Fraction – Decreased Sensitivity With Counting Methodology Fetal Fraction Adequate To Achieve Best Performance “An Aneuploidy Sample With A Lower Fetal Fraction Has A Higher Probability Of Resulting In A False Negative Result.” Thomas Musci, MD Prenatal Perspectives. Volume 1, No.2 2013.
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Chromosome 3 Chromosome 21 Counting Smaller Chromosome Lower Fraction (e.g. Chr. 21) Larger Chromosome Higher Fraction (e.g. Chr. 3)
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Chromosome 3Chromosome 21 Expected Amount: 20% 80% Countin g Observed Amount: 25% 75% How Would You Then Assess the Ratios for Chr. 21 vs. Chr. 18 vs. Chr. 13?
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SNP = Single Nucleotide Polymorphism A DNA sequence variation occurring when a single base pair (nucleotide) - A, T, C, or G – is changed. These are normal genetic changes that occur in every person
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Buffy coat = Maternal DNA Plasma = Maternal + Fetal DNA SNP Sequencing SNP Sequencing Maternal Genotype Maternal + Fetal Genotype Fetal Genotype Maternal blood SNP approach Using the Buffy Coat to Sequence Maternal Genotype Algorithm
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NIPT Test procedure The NIPT Test can be performed from week 10+0 of the pregnancy. Before carrying out a NIPT Test, the patient should be given an ultrasound scan to determine the gestational age and to check whether it is a singleton or multiple pregnancy.
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Excellent detection rate in singleton pregnancies PanoramaVerifiMaternit21Harmony testDetection ate >99% 99.7% T21 98%97%96.4%98% T18 95%93%92%93% T13
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Low false positive rate DANSR method 5 times lower than rmps
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Reliable even with heparin treatment [1] Ashoor G, Syngelaki A, Wagner M, Birdir C, Nicolaides KH: Chromosome-selective sequencing of maternal plasma cell-free DNA for first-trimester detection of trisomy 21 and trisomy 18. Am J Obstet Gynecol. 2012 Apr;206(4):322.e1-5. [2] Nicolaides KH, Syngelaki A, Ashoor G, Birdir C, Touzet G: Noninvasive prenatal testing for fetal trisomies in a routinely screened first-trimester population. Am J Obstet Gynecol. 2012 Nov;207(5):374.e1-6. [3] Norton ME, Brar H, Weiss J, Karimi A, Laurent LC, Caughey AB, Rodriguez MH, Williams J 3rd, Mitchell ME, Adair CD, Lee H, Jacobsson B, Tomlinson MW, Oepkes D, Hollemon D, Sparks AB, Oliphant A, Song K: Non-Invasive Chromosomal Evaluation (NICE) Study: results of a multicenter prospective cohort study for detection of fetal trisomy 21 and trisomy 18. Am J Obstet Gynecol. 2012 Aug;207(2):137.e1-8. [4] Sparks AB, Struble CA, Wang ET, Song K, Oliphant A: Noninvasive prenatal detection and selective analysis of cell-free DNA obtained from maternal blood: evaluation for trisomy 21 and trisomy 18. Am J Obstet Gynecol. 2012 Apr;206(4):319.e1-9. [5] Verweij EJ, Jacobsson B, van Scheltema PA, de Boer MA, Hoffer MJ, Hollemon D, Westgren M, Song K, Oepkes D: European non-invasive trisomyevaluation (EU-NITE) study: a multicenter prospective cohort study for non-invasive fetal trisomy 21 testing. Prenat Diagn. 2013 Oct;33:996-1001. [6] Juneau K, Bogard PE, Huang S, Mohseni M, Wang ET, Ryvkin P, Kingsley C, Struble CA, Oliphant A, Zahn JM: Microarray-based cell-free DNA analysis improves noninvasive prenatal testing. Fetal Diagn Ther. 2014;36:282-286. [7] Norton ME, Jacobsson B, Swamy GK, Laurent LC, Ranzini AC, Brar H, Tomlinson MW, Pereira L, Spitz JL, Hollemon D, Cuckle H, Musci TJ and Wapner RJ (Next-Study): Cell free DNA Analysis for Noninvasive Examination of Trisomy. N Engl J Med. 2015, Apr 1, DOI: 10.1056/NEJMoa1407349. [8] Stokowski R, Wang E, White K, Batey A, Jacobsson B, Brar H, Balanarasimha M, Hollemon D, Sparks A, Nicolaides K, Musci TJ..: Clinical performance of non-invasive prenatal testing (NIPT) using targeted cell-free DNA analysis in maternal plasma with microarrays or next generation sequencing (NGS) is consistent across multiple controlled clinical studies. Prenat Diagn. 2015 Sep 1. PanoramaVerifiMaternit21Harmony test YESNO YES
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Positive predictive value (PPV)
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which options are possible with different types of NIPT Tr. 21/18/13sex determinationX/Y analysis Singleton pregnancies incl. all IVF pregnancies YES Twin pregnancies incl. all IVF pregnancies/ egg donation YES (new) × More than two fetuses ×××
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NIPT results 1. Normal Result : No Specific Follow Up Necessary, Unless Ultrasound Examination Of The Fetus Reveals Anomalies +AFP Level 2. Test Failure : In 1.4 % Pregnancies Not Enough Fetal DNA : NIPT Repeated At No Extra Cost. 3. Abnormal NIPT Result => Diagnostic Tests (E.G. Amniocentesis Or Chorion Biopsy)
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Complications With NIPT 1- cfDNA-based methodologies detect Only a subset of chromosomal aberrations 2- Concerning aneuploidy of other chromosomes, molecular or congenital anomalies including neural tube defects are not excluded with NIPT. 3- Single-gene mutations? => No 4- Placental Mosaicism: i.e. Placental T21, While Normal Fetus! Note: This Is An Issue With CVS (In 1 th Trimester) As Well! 5- Still False-positive And False-negative Results (Even If At Very Low Levels) The American College Of Medical Genetics & Genomics (ACMG) Labeled The Testing “Non-invasive Prenatal Screening” Or “NIPS.”Labeled
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Thank You for your attention
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