Hongyun Zhang

Clinicalapplicationofmassivelyparallelsequencing-basedprenatal noninvasive fetal trisomy test for trisomies 21 and 18 in 11105 pregnancies with mixed risk factors

To report the performance of massively parallel sequencing (MPS) based prenatal noninvasive fetal trisomy test based on cell‐free DNA sequencing from maternal plasma in a routine clinical setting in China.

Noninvasive Fetal Trisomy (NIFTY) test: an advanced noninvasive prenatal diagnosis methodology for fetal autosomal and sex chromosomal aneuploidies

BackgroundConventional prenatal screening tests, such as maternal serum tests and ultrasound scan, have limited resolution and accuracy.MethodsWe developed an advanced noninvasive prenatal diagnosis method based on massively parallel sequencing. The Noninvasive Fetal Trisomy (NIFTY) test, combines an optimized Student’s t-test with a locally weighted polynomial regression and binary hypotheses. We applied the NIFTY test to 903 pregnancies and compared the diagnostic results with those of full karyotyping.Results16 of 16 trisomy 21, 12 of 12 trisomy 18, two of two trisomy 13, three of four 45, X, one of one XYY and two of two XXY abnormalities were correctly identified. But one false positive case of trisomy 18 and one false negative case of 45, X were observed. The test performed with 100% sensitivity and 99.9% specificity for autosomal aneuploidies and 85.7% sensitivity and 99.9% specificity for sex chromosomal aneuploidies. Compared with three previously reported z-score approaches with/without GC-bias removal and with internal control, the NIFTY test was more accurate and robust for the detection of both autosomal and sex chromosomal aneuploidies in fetuses.ConclusionOur study demonstrates a powerful and reliable methodology for noninvasive prenatal diagnosis.

Non-invasive prenatal testing for fetal chromosomal abnormalities by low-coverage whole-genome sequencing of maternal plasma DNA: review of 1982 consecutive cases in a single center

To review the performance of non‐invasive prenatal testing (NIPT) by low‐coverage whole‐genome sequencing of maternal plasma DNA at a single center.

Secondary findings from non‐invasive prenatal testing for common fetal aneuploidies by whole genome sequencing as a clinical service

To report secondary or additional findings arising from introduction of non‐invasive prenatal testing (NIPT) for aneuploidy by whole genome sequencing as a clinical service.

Fetal aneuploidy screening by maternal plasma DNA sequencing: ‘False positive’ due to confined placental mosaicism

INTRODUCTION Non-invasive prenatal testing (NIPT) of fetal Down syndrome by maternal plasma DNA sequencing have been proven to be a highly efficient screening test, with both sensitivity and specificity of over 99%. This new screening test has been recently put into clinical service used either as a primary or secondary screening test for aneuploidy. There is increasing evidence that this new technology is also highly efficient in the screening of aneuploidies involving other chromosomes. Research so far has suggested that these cell-free DNAs are from the placenta. Therefore, an abnormal NIPT result could be due to conditions other than fetal trisomy. We report here a case in which the NIPT was positive for trisomy 22 because of confined placental mosaicism.

Non-invasive prenatal screening of fetal Down syndrome by maternal plasma DNA sequencing in twin pregnancies

Non-invasive prenatal screening for fetal Down syndrome (NIFTY) by maternal plasma sequencing was performed in 12 subjects with twin pregnancies, including 11 with normal fetuses and 1 with discordant fetal Trisomy 21. For every sample, it was processed, sequenced and reported as soon as it was collected as other clinical samples for singleton pregnancies. The NIFTY test was negative in the 11 pregnancies carried normal fetuses, and was positive (high risk) in the case with discordant fetal Trisomy 21. The sensitivity and specificity were both 100%. This small case series suggested the NIFTY as a screening test for fetal Trisomy 21 is feasible in twin pregnancies.

Noninvasive prenatal testing of trisomies 21 and 18 by massively parallel sequencing of maternal plasma DNA in twin pregnancies.

The objective of this study is to assess the performance of noninvasive prenatal testing for trisomies 21 and 18 on the basis of massively parallel sequencing of cell‐free DNA from maternal plasma in twin pregnancies.

Noninvasive prenatal genetic testing for fetal aneuploidy detects maternal trisomy X

Trisomy X is a sex chromosomal abnormality with a variable phenotype caused by the presence of an extra X chromosome in females (47,XXX instead of 46,XX). It is the most common female chromosomal abnormality, occurring in approximately 1 in 1000 female births. There is considerable variation in the phenotype, from asymptomatic and very mildly affected to significant physical and psychological features, leading only 10% of diagnosis ratio for those individuals with trisomy X. Current prenatal diagnosis of trisomy X relies on invasive prenatal tests such as karyotyping analysis. Although such tests allow accurate diagnosis, wide clinical use is limited by its complex operations and invasive nature with a 0.5% to 1% of procedure-related miscarriage. Recently, a newmethod based on massively parallel sequencing for cell-free DNA in maternal plasma was developed to detect fetal trisomy disorders. A rapid response statement from a committee on behalf of the Board of the International Society for Prenatal Diagnosis showed that the test currently available is only for fetal trisomy 21 and trisomy 18, which constitutes only about half of the fetal aneuploidy that would be identified through amniocentesis or CVS. Prior studies have shown that this massively parallel sequencing based noninvasive fetal trisomy test (the NIFTY test, which has no relationship with the ‘NIFTY’ trial on noninvasive prenatal diagnosis that was sponsored by the US National Institutes of Health) can not only detect trisomy 21 and trisomy 18, but also sex chromosomal aneuploidies. However, the effect of the maternal genetic background on the performance of the NIFTY test is not clear. Here we present a case in which maternal chromosome X materials affect the performance of the NIFTY. This case may provide a useful complement for the clinical application of the NIFTY test.

Effects of Maternal and Fetal Characteristics on Cell-Free Fetal DNA Fraction in Maternal Plasma.

Objective: To study factors that influence the concentration of cell-free fetal DNA (fetal fraction) using a large clinical data set of pregnancies with male fetus. Method: A retrospective analysis of 23 067 pregnancies that received noninvasive prenatal testing from January 2012 to October 2013, including 22 650 normal singleton pregnancies (control group) and 417 pregnancies with aneuploidy, twin pregnancy, or various maternal conditions including preexisting hypertension, preexisting diabetes, hyperthyroidism, and carrier of the surface antigen of the hepatitis B virus (HBsAg; study group). Multiples of the median (MoM) analysis was performed in the control group to derive gestation and body mass index (BMI)-corrected fetal fraction. The effects of study group conditions on fetal fraction were examined by calculating the ratio of MoM (RMoM) values. Results: Fetal fraction showed a positive correlation with gestational age (r2 = .10, P < .001) and increased rapidly after the 21 weeks of gestation (r2 = .26, P < .001). Negative association with maternal BMI was found with fetal fraction (r2 = .04, P < .001). In study group, fetal fraction was higher among pregnant women with a trisomy 21 fetus (RMoM = 1.24, P < .001) and lower among trisomy 18 (RMoM = 0.84, P < .001). A 1.6-fold incensement of fetal fraction was observed in twin fetuses comparing to singleton pregnancy (RMoM = 1.62, P < .001). Women with preexisting hypertension had significantly lower fetal fraction (RMoM = 0.85, P = .02). Preexisting diabetes, hyperthyroidism, or carrier of HBsAg did not affect fetal fraction. Conclusion: The fetal fraction was affected by fetal aneuploidy, maternal BMI, and the number of gestation. Maternal preexisting of hypertension appeared to reduce fetal fraction.

Noninvasive prenatal testing (NIPT) in twin pregnancies with treatment of assisted reproductive techniques (ART) in a single center.

The objective of the study is to report the performance of noninvasive prenatal testing (NIPT) in twin pregnancies after the treatment of assisted reproductive technology (ART).