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Non-invasive Prenatal Trisomy test. A safe prenatal testing for fetal chromosomal aneuploidy . Leon Liang BGI Health Europe. Common fetal aneuploidy. Others: Turner syndrome (XO), Klinefelter syndrome (XXY), triple X syndrome (XXX), etc. Current screening & diagnostic tests.
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Non-invasive Prenatal Trisomy test A safe prenatal testing for fetal chromosomal aneuploidy Leon Liang BGI Health Europe
Common fetal aneuploidy Others: Turner syndrome (XO), Klinefelter syndrome (XXY), triple X syndrome (XXX), etc.
Current screening & diagnostic tests * Data present in 5% false positive rate Fergal D, Jacob A, et al. The New England Journal of Medicine, 2005
NIFTY Screening tests Diagnostic tests • Serum biochemical test; ultrasound scan • Non-invasive • Cheap • Less accurate • Low detection rate • High false positive rate • Karyotyping (G-banding or FISH) • Invasive • Expensive • Highly accurate • High detection rate • Low false positive rate
What’s NIFTY test? • Non-Invasive Fetal TrisomY • A superior screening test • High detection rate and low false positive rate • Non-invasive method based on NGS and bioinformatics • Analysis of fetal cell free DNA in maternal plasma • Evaluate the likelihood of fetal trisomy 21, 18, and 13
Features of NIFTY New detection technology based on NGS; Sensitivity and specificity > 99% No risks of intrauterine infection and miscarriage NIFTY Fetal trisomy risk can be evaluated as early as 12 gestational week Reduce clinical pressure of unnecessary invasive tests Only 5ml of peripheral blood is needed; easy to handle in clinical practice
Scientific discovery • Fundamental Features of Cell-Free Fetal DNA • Short fragments of 145-200bp, derived from placental trophocytes • 970 times greater than fetal cells DNA in maternal blood. • Detectable in maternal plasma from the 5th week of gestation. • Concentration increase as the gestation age grows • Disappears soon after childbirth.
Sequencing revolution NGS Sanger
Principle of NIFTY Normal T-21 Plasma DNA Total cfDNA sequencing Chr6 Chr18 ChrX Chr21 Chr7 Chr13 Chr11 ChrY Reads alignment ….. Reads count Bioinformatics analysis
Clinical validation in 3464 samples • Study design and aim: • Validation of the NIFTY in predicting the fetal risk of trisomy 21, 18, and 13 in high risk population by a double blind test • Evaluation of sensitivity and specificity of the NIFTY by comparing to karyotyping result (clinical gold standard) • provide supports for large-scale test in real clinical setting
NIFTY results in 3464 samples *caused by insufficient sequencing depth
Large scale clinical test (2009-2011) Qualified maternal blood samples (n=11184) • Gestational week from 9 – 28 weeks, averagely 20 weeks • Maternal age from 18 – 45 years, averagely 31 years • 4522 screening test high risk pregnancies • 2426 screening test low risk pregnancies • 2720 other high risk factors (AMA, abnormal NT, previous abnormal pregnancy, etc.) • 1387 screening not done 0.7% of all samples Unable to produce results (n=79; failed DNA extraction, library construction, or sequencing) 99.3% of all samples Pregnant women with NIFTY results (n=11105) Positive (n=190) Negative (n=10915) Shan Dan, et al., Prenatal Diagnosis, 2012: p. 1-8.
NIFTY results in 11105 samples Shan Dan, et al., Prenatal Diagnosis, 2012: p. 1-8.
Other rare aneuploidies A T21 case was missed by biochemical screening Sample ID: PDP10003761 Age: 31 Screening test: 1/510(Low risk) NIFTY: T21 Karyotyping: 47, XX, +21
T9 Sample ID: PDB11AJ00026 Age: 41 NIFTY: T9 Karyotyping: T9
T16 Sample ID: PDB11AJ00783 Age: 30 NIFTY: T16 FISH: T16
Mosaic T21 Sample ID: PDB12AO00267 Age: 38 NIFTY: T21 Karyotyping: 47, XX, +21 (88%)
T21-T7-XXY complex placental mosaic Sample ID: PDB12AL00732 Age: 37 NIFTY: T21-T7-XXY/XY Karyotyping: CVS T21-T7-XXY/XY; AF euploid
NIFTY clinical pipeline AMA, Previous affected fetus, Recurrent miscarriage, Aneuploidy background
Test workflow Hospital • Post-test counseling BGI Clinical Laboratories: 10 days
Sample Management System • Unique Identification • Sample Location • Storage Capability Laboratory System Effective lab space separation Progressively decreased pressure Restricted traffic flow
NIFTY is not suitable for Detection of balanced rearrangements and low level of mosaicism The pregnant woman is a chromosomal aneuploidy carrier If either of the parent has chromosomal structural abnormalities e.g. duplication, deletion, translocation, etc. If the pregnant woman receives allogenic DNA importation prior to NIFTY e.g. blood transfusion, transplantation, stem cell therapy, etc.
Report Genetic testing report Low risk: the fetus is unlikely to be T21, T18, or T13. No special medical procedure is recommended. Routine prenatal checks is suggested. High risk: the fetus is likely to be T21, or T18, or T13. diagnostic procedure such as amniocentesis or cordocentesis is recommended. More than 98% of cases
Delay notification QC: Caused by either the experiment or blood sample quality; need to repeat the experiment Data fluctuation: Caused by high data deviation; need to repeat the experiment cfDNA concentration low: Need to repeat the experiment If repeating experiment still cannot solve the problem, blood re-sampling is required.
Re-sampling notification QC: Caused by poor blood sample quality cfDNA concentration low Previous NIFTY failed to produce informative result, and gestational age is more than 22 weeks
NIFTY express Validated on 1647 samples Performed on Ion Proton platform, extremely fast Performed in Czech Republic BGI-GENNET co-lab. EU based service. Similar price
NIFTY plus Detection of Microdeletion syndromes Non-invasive Monogenic disease detection Results of other prenatal tests such as biochemical and ultrasound tests should be considered. Diagnostic procedure such as amniocentesis/cordocentesis is suggested.
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