scholarly journals Alkaline phosphatase ınterference in an unconjugated estriol assay causing a false positive Down syndrome screening result

2018 ◽  
Vol 44 (1) ◽  
pp. 108-112
Author(s):  
Zeynep Yildiz ◽  
Özlem Çakır Madenci ◽  
Asuman Orçun ◽  
Özlem Hürmeydan ◽  
Lale Köroğlu Dağdelen ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Down Syndrome ◽  
False Positive ◽  
Screening Test ◽  
Three Dimensional ◽  
Serum Samples ◽  
Cell Free Fetal Dna ◽  
Second Trimester Screening ◽  
Unconjugated Estriol ◽  
Assay Interference

Abstract Objective Decreased unconjugated estriol (uE3) concentrations increase calculated risk of Down syndrome. Therefore, falsely low uE3, due to assay interference, have the potential to cause false-positive screening results. Here we present a 35 years old woman with a pregnancy of 17+2 weeks. Materials and methods Second-trimester screening test was performed on the UniCelDxI 800 (Beckman Coulter, Brea, CA, USA) analyzer and her uE3 level was 0.21 ng/mL (0.21 MoM). Risk calculated for DS was 1/8. Measurements were repeated on IMMULITE 2000 XPi (Siemens Healthcare Diagnostics Inc., USA). uE3 result was 0.614 ng/mL (0.97 MoM). The risk for DS was negative with this system. There was no sign of fetal anomaly on three-dimensional ultrasound examination and cell-free fetal DNA screening test. We suspected assay interference for uE3. Results Serial dilutions of serum samples revealed nonlinearity. 36.3% increase was observed with heterophile antibody blocking tubes. The post-polyethylene glycol treatment resulted approximately the same uE3 levels as IMMULITE system. Addition of alkaline phosphatase Scavenger to serum increased the result by 90% showing that falsely low E3 result was due to an interferent reacting on assay medium. Conclusion Laboratories should be aware that falsely low uE3 results due to interference may be obtained.

22 Fetal down syndrome is associated with increased cell-free fetal DNA levels in archived maternal serum samples

2001 ◽  
Vol 185 (6) ◽  
pp. S79 ◽  
Author(s):  
Thomas Lee ◽  
Erik Leshane ◽  
Geralyn Messerlian ◽  
Jacob Canick ◽  
Marshall Carpenter ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Maternal Serum ◽  
Serum Samples ◽  
Fetal Dna ◽  
Cell Free Fetal Dna

scholarly journals Non-invasive prenatal cell-free fetal DNA testing for down syndrome and other chromosomal abnormalities

2015 ◽  
Vol 84 (11) ◽  
Author(s):  
Darija Strah ◽  
Petra Ovniček ◽  
Janez Bernik
Keyword(s):  
Down Syndrome ◽  
Confidence Interval ◽  
Screening Test ◽  
Chromosomal Abnormalities ◽  
Fetal Loss ◽  
Dna Testing ◽  
Non Invasive ◽  
Fetal Dna ◽  
Triple X Syndrome ◽  
Cell Free Fetal Dna

Background: Chorionic villus sampling and amniocentesis as definitive diagnostic procedures represent a gold standard for prenatal diagnosis of chromosomal abnormalities. The methods are invasive and lead to a miscarriage and fetal loss in approximately 0.5–1 %. Non-invasive prenatal DNA testing (NIPT) is based on the analysis of cell-free fetal DNA from maternal blood. It represents a highly accurate screening test for detecting the most common fetal chromosomal abnormalities. In our study we present the results of NIPT testing in the Diagnostic Center Strah, Slovenia, over the last 3 years.Methods: In our study, 123 pregnant women from 11th to 18th week of pregnancy were included. All of them had First trimester assessment of risk for trisomy 21, done before NIPT testing.Results: 5 of total 6 high-risk NIPT cases (including 3 cases of Down syndrome and 2 cases of Klinefelter’s syndrome) were confirmed by fetal karyotyping. One case–Edwards syndrome was false positive. Patau syndrome, triple X syndrome or Turner syndrome were not observed in any of the cases. Furthermore, there were no false negative cases reported. In general, NIPT testing had 100 % sensitivity (95 % confidence interval: 46.29 %–100.00 %) and 98.95 % specificity (95 % confidence interval: 93.44 %–99.95 %). In determining Down syndrome alone, specificity (95 % confidence interval: 95.25 %- 100.00 %) and sensitivity (95 % confidence interval: 31.00 %–100.00 %) turned out to be 100 %. In 2015, the average turnaround time for analysis was 8.3 days from the day when the sample was taken. Repeated blood sampling was required in 2 cases (redraw rate = 1.6 %).Conclusions: Our results confirm that NIPT represents a fast, safe and highly accurate advanced screening test for most common chromosomal abnormalities. In current clinical practice, NIPT would significantly decrease the number of unnecessary invasive procedures and the rate of fetal loss caused by invasive diagnostics.

Down syndrome and cell-free fetal DNA in archived maternal serum

2002 ◽  
Vol 187 (5) ◽  
pp. 1217-1221 ◽  
Author(s):  
Thomas Lee ◽  
Erik S. LeShane ◽  
Geralyn M. Messerlian ◽  
Jacob A. Canick ◽  
Antonio Farina ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Maternal Serum ◽  
Fetal Dna ◽  
Cell Free Fetal Dna

scholarly journals Hyperglycosylated Human Chorionic Gonadotropin (Invasive Trophoblast Antigen) Immunoassay: A New Basis for Gestational Down Syndrome Screening

1999 ◽  
Vol 45 (12) ◽  
pp. 2109-2119 ◽  
Author(s):  
Laurence A Cole ◽  
Shohreh Shahabi ◽  
Utku A Oz ◽  
Ray O Bahado-Singh ◽  
Maurice J Mahoney
Keyword(s):  
Down Syndrome ◽  
False Positive ◽  
False Positive Rate ◽  
Normal Karyotype ◽  
Screen Test ◽  
Β Subunit ◽  
Second Trimester ◽  
Marker Test ◽  
Positive Rate ◽  
Down Syndrome Screening

Abstract Background: Serum human chorionic gonadotropin (hCG) and hCG free β-subunit tests are used in combination with unconjugated estriol and α-fetoprotein in the triple screen test, and with the addition of inhibin-A in the quadruple marker test for detecting Down syndrome in the second trimester of pregnancy. These tests have a limited detection rate for Down syndrome: ∼40% for hCG or free β-subunit alone, ∼60% for the triple screen test, and ∼70% for the quadruple marker test, all at 5%, or a relatively high, false-positive rate. New tests are needed with higher detection and lower false rates. Hyperglycosylated hCG (also known as invasive trophoblast antigen or ITA) is a new test. It specifically detects a unique oligosaccharide variant of hCG associated with Down syndrome pregnancies. We evaluated this new Down syndrome-directed test in prenatal diagnosis. Methods: Hyperglycosylated hCG was measured in urine samples from women undergoing amniocentesis for advanced maternal age concerns at 14–22 weeks of gestation, 1448 with normal karyotype and 39 with Down syndrome fetuses. Results: The median hyperglycosylated hCG value was 9.5-fold higher in Down syndrome cases (9.5 multiples of the normal karyotype median). The single test detected 80% of Down syndrome cases at a 5% false-positive rate. Urine hyperglycosylated hCG was combined with urine β-core fragment (urine breakdown product of serum hCG free β-subunit), serum α-fetoprotein, and maternal age-related risk. This urine-serum combination detected 96% of Down syndrome cases at a 5% false-positive rate, 94% of cases at a 3% false-positive rate, and 71% of cases at a 1% false-positive rate. These detection rates exceed those of any previously reported combination of biochemical markers. Conclusions: Hyperglycosylated hCG is a new base marker for Down syndrome screening in the second trimester of pregnancy. The measurement of hyperglycosylated hCG can fundamentally improve the performance of Down syndrome screening protocols.

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