scholarly journals Microsatellite Markers within —SEA Breakpoints for Prenatal Diagnosis of HbBarts Hydrops Fetalis

2007 ◽  
Vol 53 (2) ◽  
pp. 173-179 ◽  
Author(s):  
Sherry Sze Yee Ho ◽  
Samuel S Chong ◽  
Evelyn SC Koay ◽  
Yiong Huak Chan ◽  
Ponnusamy Sukumar ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Microsatellite Markers ◽  
Genetic Material ◽  
Simultaneous Detection ◽  
Hydrops Fetalis ◽  
Deletion Syndrome ◽  
Correct Identification ◽  
Fetal Dna ◽  
Cell Free Fetal Dna ◽  
Maternal Contamination

Abstract Background: We sought to develop a rapid prenatal diagnostic test for simultaneous detection of HbBarts hydrops fetalis and exclusion of maternal contamination. Methods: We developed a multiplex quantitative fluorescent PCR (QF-PCR) test that detects the presence/ absence of 2 microsatellite markers (16PTEL05/16PTEL06) located within breakpoints of the Southeast Asia (—SEA) deletion. HbBarts hydrops fetalis (—SEA/—SEA) is diagnosed by absence of both markers, and maternal contamination of fetal DNA is excluded by absence of noninherited maternal alleles. Fetal and parental DNA samples from 50 families were analyzed in a blinded clinical validation study, and QF-PCR results were compared with their respective molecular genotypes. Results: The multiplex QF-PCR results included correct diagnoses of HbBarts hydrops fetalis in 11 of the fetuses tested, correct verification as unaffected in 20 fetuses, and correct identification as either carriers (αα/—SEA) or unaffected homozygotes in 18. Misidentification as unaffected occurred for 1 carrier. Sensitivity for diagnosis of HbBarts hydrops fetalis was 100% [lower 95% confidence interval, 76.2%], and specificity was 100% (lower 95% confidence interval, 92.6%). None of the samples tested showed any traces of noninherited maternal alleles; thus false-positives because of maternal contamination were eliminated. Conclusions: In this QF-PCR method, detection of maternally and paternally inherited fetal alleles allowed diagnosis of the double-deletion syndrome, and the ability to differentiate between these alleles allowed simultaneous exclusion of maternal contamination of the fetal genetic material. This novel strategy using cell-free fetal DNA in maternal plasma could form the basis for noninvasive testing for HbBarts hydrops fetalis.

Application of real-time PCR of sex-independent insertion-deletion polymorphisms to determine fetal sex using cell-free fetal DNA from maternal plasma

2015 ◽  
Vol 53 (8) ◽  
Author(s):  
Sherry Sze Yee Ho ◽  
Angela Barrett ◽  
Henna Thadani ◽  
Cecille Laureano Asibal ◽  
Evelyn Siew-Chuan Koay ◽  
...  
Keyword(s):  
Real Time ◽  
Y Chromosome ◽  
Real Time Pcr ◽  
Genetic Material ◽  
Maternal Plasma ◽  
Fetal Sex ◽  
Female Fetus ◽  
Non Invasive ◽  
Fetal Dna ◽  
Cell Free Fetal Dna

AbstractPrenatal diagnosis of sex-linked disorders requires invasive procedures, carrying a risk of miscarriage of up to 1%. Cell-free fetal DNA (cffDNA) present in cell-free DNA (cfDNA) from maternal plasma offers a non-invasive source of fetal genetic material for analysis. Detection of Y-chromosome sequences in cfDNA indicates presence of a male fetus; in the absence of a Y-chromosome signal a female fetus is inferred. We aimed to validate the clinical utility of insertion-deletion polymorphisms (INDELs) to confirm presence of a female fetus using cffDNA.Quantitative real-time PCR (qPCR) for the Y-chromosome-specific sequence,Fetal sex was correctly determined in 77/82 (93.9%) cfDNA samples.We have validated a non-invasive prenatal test to confirm fetal sex as early as 6 gestational weeks using cffDNA from maternal plasma.

scholarly journals Size Separation of Circulatory DNA in Maternal Plasma Permits Ready Detection of Fetal DNA Polymorphisms

2004 ◽  
Vol 50 (6) ◽  
pp. 1002-1011 ◽  
Author(s):  
Ying Li ◽  
Bernhard Zimmermann ◽  
Corinne Rusterholz ◽  
Anjeung Kang ◽  
Wolfgang Holzgreve ◽  
...  
Keyword(s):  
Microsatellite Markers ◽  
Dna Sequences ◽  
Maternal Plasma ◽  
Biochemical Properties ◽  
Chromosome 21 ◽  
Dna Polymorphisms ◽  
Plasma Dna ◽  
Genetic Traits ◽  
Fetal Dna ◽  
Cell Free Fetal Dna

Abstract Background: Analysis of fetal DNA in maternal plasma has recently been introduced as a new method for noninvasive prenatal diagnosis, particularly for the analysis of fetal genetic traits, which are absent from the maternal genome, e.g., RHD or Y-chromosome-specific sequences. To date, the analysis of other fetal genetic traits has been more problematic because of the overwhelming presence of maternal DNA sequences in the circulation. We examined whether different biochemical properties can be discerned between fetal and maternal circulatory DNA. Methods: Plasma DNA was examined by agarose gel electrophoresis. The fractions of fetal and maternal DNA in size-fractionated fragments were assayed by real-time PCR. The determination of paternally and maternally inherited fetal genetic traits was examined by use of highly polymorphic chromosome-21-specific microsatellite markers. Results: Size fractionation of circulatory DNA indicated that the major portion of cell-free fetal DNA had an approximate molecular size of <0.3 kb, whereas maternally derived sequences were, on average, considerably larger than 1 kb. Analysis of size-fractionated DNA (≤0.3 kb) from maternal plasma samples facilitated the ready detection of paternally and maternally inherited microsatellite markers. Conclusions: Circulatory fetal DNA can be enriched by size selection of fragment sizes less than ∼0.3kb. Such selection permits easier analysis of both paternally and maternally inherited DNA polymorphisms.

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.

Diagnostic Value of Non-Invasive Prenatal Screening of β-thalassemia by Cell Free Fetal DNA and Fetal NRBC

2019 ◽  
Vol 19 (2) ◽  
pp. 105-111
Author(s):  
Nadia Shafei ◽  
Mohammad Saeed Hakhamaneshi ◽  
Massoud Houshmand ◽  
Siavash Gerayeshnejad ◽  
Fardin Fathi ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Multiple Displacement Amplification ◽  
Diagnostic Value ◽  
Diagnostic Methods ◽  
Beta Thalassemia ◽  
Non Invasive ◽  
Fetal Dna ◽  
Prenatal Diagnostic ◽  
Cell Free Fetal Dna ◽  
Invasive Techniques

Background: Beta thalassemia is a common disorder with autosomal recessive inheritance. The most prenatal diagnostic methods are the invasive techniques that have the risk of miscarriage. Now the non-invasive methods will be gradually alternative for these invasive techniques. Objective: The aim of this study is to evaluate and compare the diagnostic value of two non-invasive diagnostic methods for fetal thalassemia using cell free fetal DNA (cff-DNA) and nucleated RBC (NRBC) in one sampling community. Methods: 10 ml of blood was taken in two k3EDTA tube from 32 pregnant women (mean of gestational age = 11 weeks), who themselves and their husbands had minor thalassemia. One tube was used to enrich NRBC and other was used for cff-DNA extraction. NRBCs were isolated by MACS method and immunohistochemistry; the genome of stained cells was amplified by multiple displacement amplification (MDA) procedure. These products were used as template in b-globin segments PCR. cff-DNA was extracted by THP method and 300 bp areas were recovered from the agarose gel as fetus DNA. These DNA were used as template in touch down PCR to amplify b-globin gen. The amplified b-globin segments were sequenced and the results compared with CVS resul. Results: The data showed that sensitivity and specificity of thalassemia diagnosis by NRBC were 100% and 92% respectively and sensitivity and specificity of thalassemia diagnosis by cff-DNA were 100% and 84% respectively. Conclusion: These methods with high sensitivity can be used as screening test but due to their lower specificity than CVS, they cannot be used as diagnostic test.

scholarly journals Noncanonical crRNAs derived from host transcripts enable multiplexable RNA detection by Cas9

Science ◽  
2021 ◽  
pp. eabe7106
Author(s):  
Chunlei Jiao ◽  
Sahil Sharma ◽  
Gaurav Dugar ◽  
Natalia L. Peeck ◽  
Thorsten Bischler ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Genetic Material ◽  
Simultaneous Detection ◽  
Type Ii ◽  
Rna Detection ◽  
Single Base ◽  
Dna Targeting ◽  
Single Base Resolution ◽  
Rna Complexes

CRISPR-Cas systems recognize foreign genetic material using CRISPR RNAs (crRNAs). In Type II systems, a trans-activating crRNA (tracrRNA) hybridizes to crRNAs to drive their processing and utilization by Cas9. While analyzing Cas9-RNA complexes from Campylobacter jejuni, we discovered tracrRNA hybridizing to cellular RNAs, leading to formation of “noncanonical” crRNAs capable of guiding DNA targeting by Cas9. Our discovery inspired the engineering of reprogrammed tracrRNAs that link the presence of any RNA-of-interest to DNA targeting with different Cas9 orthologs. This capability became the basis for a multiplexable diagnostic platform termed LEOPARD (Leveraging Engineered tracrRNAs and On-target DNAs for PArallel RNA Detection). LEOPARD allowed simultaneous detection of RNAs from different viruses in one test and distinguished SARS-CoV-2 and its D614G variant with single-base resolution in patient samples.

scholarly journals Non-Invasive Prenatal Testing: Current Perspectives and Future Challenges

Genes ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 15
Author(s):  
Luigi Carbone ◽  
Federica Cariati ◽  
Laura Sarno ◽  
Alessandro Conforti ◽  
Francesca Bagnulo ◽  
...  
Keyword(s):  
Prenatal Screening ◽  
Prenatal Testing ◽  
Non Invasive ◽  
Fetal Dna ◽  
Cell Free Fetal Dna ◽  
Common Causes ◽  
Future Challenges ◽  
Neurodevelopmental Impairment ◽  
Fetal Aneuploidies ◽  
Made In

Fetal aneuploidies are among the most common causes of miscarriages, perinatal mortality and neurodevelopmental impairment. During the last 70 years, many efforts have been made in order to improve prenatal diagnosis and prenatal screening of these conditions. Recently, the use of cell-free fetal DNA (cff-DNA) testing has been increasingly used in different countries, representing an opportunity for non-invasive prenatal screening of pregnant women. The aim of this narrative review is to describe the state of the art and the main strengths and limitations of this test for prenatal screening of fetal aneuploidies.

Inability to Detect Cell Free Fetal DNA in the Urine of Normal Pregnant Women nor in Those Affected by Preeclampsia Associated HELLP Syndrome

2003 ◽  
Vol 10 (8) ◽  
pp. 503-508 ◽  
Author(s):  
Ying Li ◽  
Xiao Yan Zhong ◽  
Anjeung Kang ◽  
Carolyn Troeger ◽  
Wolfgang Holzgreve ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Hellp Syndrome ◽  
Fetal Dna ◽  
Cell Free Fetal Dna
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