scholarly journals Using Digital Polymerase Chain Reaction to Detect Single-Nucleotide Substitutions Induced by Genome Editing

2016 ◽  
Vol 2016 (8) ◽  
pp. pdb.prot086801 ◽  
Author(s):  
Yuichiro Miyaoka ◽  
Amanda H. Chan ◽  
Bruce R. Conklin
Keyword(s):  
Polymerase Chain Reaction ◽  
Genome Editing ◽  
Chain Reaction ◽  
Nucleotide Substitutions ◽  
Single Nucleotide ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

scholarly journals Validation of ctDNA Quality Control Materials Through a Precompetitive Collaboration of the Foundation for the National Institutes of Health

2021 ◽  
pp. 910-920
Author(s):  
P. Mickey Williams ◽  
Thomas Forbes ◽  
Steven P. Lund ◽  
Kenneth D. Cole ◽  
Hua-Jun He ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Quality Control ◽  
Copy Number ◽  
National Institutes Of Health ◽  
Single Nucleotide Variants ◽  
Chain Reaction ◽  
Single Nucleotide ◽  
Quality Control Materials ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

PURPOSE We report the results from a Foundation for the National Institutes of Health Biomarkers Consortium project to address the absence of well-validated quality control materials (QCMs) for circulating tumor DNA (ctDNA) testing. This absence is considered a cause of variance and inconsistencies in translating ctDNA results into clinical actions. METHODS In this phase I study, QCMs with 14 clinically relevant mutations representing single nucleotide variants, insertions or deletions (indels), translocations, and copy number variants were sourced from three commercial manufacturers with variant allele frequencies (VAFs) of 5%, 2.5%, 1%, 0.1%, and 0%. Four laboratories tested samples in quadruplicate using two allele-specific droplet digital polymerase chain reaction and three (amplicon and hybrid capture) next-generation sequencing (NGS) panels. RESULTS The two droplet digital polymerase chain reaction assays reported VAF values very close to the manufacturers’ claimed concentrations for all QCMs. NGS assays reported most single nucleotide variants and indels, but not translocations, close to the expected VAF values. Notably, two NGS assays reported lower VAF than expected for all translocations in all QCM mixtures, possibly related to technical challenges detecting these variants. The ability to call ERBB2 copy number amplifications varied across assays. All three QCMs provided valuable insight into assay precision. Each assay across all variant types demonstrated dropouts at 0.1%, suggesting that the QCM can serve for testing of an assay’s limit of detection with confidence claims for specific variants. CONCLUSION These results support the utility of the QCM in testing ctDNA assay analytical performance. However, unique designs and manufacturing methods for the QCM, and variations in a laboratory’s testing configuration, may require testing of multiple QCMs to find the best reagents for accurate result interpretation.

scholarly journals Digital Droplet PCR for SARS-CoV-2 Resolves Borderline Cases

2021 ◽  
Author(s):  
Jing Xu ◽  
Timothy Kirtek ◽  
Yan Xu ◽  
Hui Zheng ◽  
Huiyu Yao ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Limit Of Detection ◽  
False Negative ◽  
Accurate Method ◽  
Viral Envelope ◽  
Chain Reaction ◽  
Borderline Cases ◽  
Droplet Pcr ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

Abstract Objectives The Bio-Rad SARS-CoV-2 ddPCR Kit (Bio-Rad Laboratories) was the first droplet digital polymerase chain reaction (ddPCR) assay to receive Food and Drug Administration (FDA) Emergency Use Authorization approval, but it has not been evaluated clinically. We describe the performance of ddPCR—in particular, its ability to confirm weak-positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) results. Methods We clinically validated the Bio-Rad Triplex Probe ddPCR Assay. The limit of detection was determined by using serial dilutions of SARS-CoV-2 RNA in an artificial viral envelope. The ddPCR assay was performed according to the manufacturer’s specifications on specimens confirmed to be positive (n = 48) or negative (n = 30) by an FDA-validated reverse transcription–polymerase chain reaction assay on the m2000 RealTime system (Abbott). Ten borderline positive cases were also evaluated. Results The limit of detection was 50 copies/mL (19 of 20 positive). Forty-seven specimens spanning a range of quantification cycles (2.9-25.9 cycle numbers) were positive by this assay (47 of 48; 97.9% positive precent agreement), and 30 negative samples were confirmed as negative (30 of 30; 100% negative percent agreement). Nine of 10 borderline cases were positive when tested in triplicate. Conclusions The ddPCR of SARS-CoV-2 is an accurate method, with superior sensitivity for viral RNA detection. It could provide definitive evaluation of borderline positive cases or suspected false-negative cases.

Comparison of Droplet Digital Polymerase Chain Reaction (ddPCR) and Real-Time Quantitative Polymerase Chain Reaction (qPCR) in Detecting Neonatal Invasive Fungal Infections

2021 ◽  
Vol 11 (3) ◽  
pp. 373-379
Author(s):  
Huitao Li ◽  
Xueyu Chen ◽  
Xiaomei Qiu ◽  
Weimin Huang ◽  
Chuanzhong Yang
Keyword(s):  
Polymerase Chain Reaction ◽  
Limit Of Detection ◽  
Quantitative Polymerase Chain Reaction ◽  
Diagnostic Methods ◽  
Chain Reaction ◽  
Fungal Isolation ◽  
Blood Samples ◽  
Fungal Strains ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

Invasive fungal infection (IFI) is the leading cause of death in neonatal patients, yet the diagnosis of IFI remains a major challenge. At present, most IFI laboratory diagnostic methods are based on classical, but limited, methods such as fungal isolation and culture and histopathological examination. Recently, quantitative polymerase chain reaction (qPCR) and droplet digital polymerase chain reaction (ddPCR) technology have been adopted to quantify nucleic-acid identification. In this study, we established qPCR and ddPCR assays for IFI diagnosis and quantification. qPCR and ddPCR were carried out using identical primers and probe for the amplification of 18S rRNA. Assay results for three fungal strains were positive, whereas ten non-fungal strains had negative results, indicating 100% specificity for both ddPCR and qPCR methods. Genomic DNA of Candida albicans was tested after a serial dilution to compare the sensitivity of the two PCR methods. The limit of detection of ddPCR was 3.2 copies/L, which was a ten-fold increase compared with that of the qPCR method (32 copies/L). Blood samples from 127 patients with high-risk factors and clinical symptoms for IFI were collected from a NICU in Shenzhen, China, and analyzed using qPCR and ddPCR. Thirty-four blood samples from neonates had a proven or probable diagnosis of IFI, and 25 of these were positive by qPCR, whereas 30 were positive by ddPCR. Among the 93 blood samples from neonates who had a possible IFI or no IFI, 24 were positive using qPCR, and 7 were positive using ddPCR. In conclusion, ddPCR is a rapid and accurate pan-fungal detection method and provides a promising prospect for IFI clinical screening.

scholarly journals Identifikasi Keragaman Gen DGAT1 serta Asosiasinya terhadap Karakteristik Karkas dan Sifat Perlemakan Domba

2019 ◽  
Vol 6 (2) ◽  
pp. 259
Author(s):  
Asep Gunawan ◽  
Ratna Sholatia Harahap ◽  
Kasita Listyarini ◽  
Cece Sumantri
Keyword(s):  
Polymerase Chain Reaction ◽  
Single Nucleotide Polymorphism ◽  
Fragment Length Polymorphism ◽  
Nucleotide Polymorphism ◽  
Chain Reaction ◽  
Single Nucleotide ◽  
Dgat1 Gene ◽  
Pcr Rflp ◽  
Polymerase Chain ◽  
Restriction Fragment Length

ABSTRAK Karakteristik karkas dan sifat perlemakan pada daging domba dikontrol oleh banyak gen salah satunya gen DGAT1 (Diacylglycerol Acyltransferasel 1). Penelitian ini bertujuan mengidentifikasi SNP (Single Nucleotide Polymorphism) gen DGAT1 pada titik mutasi g.8539 C>T dan asosiasinya terhadap karakteristik karkas dan sifat perlemakan pada domba Indonesia. Total sampel domba yang digunakan sebanyak 150 buah terdiri dari 35 sampel domba compass agrinak (DCA), 36 sampel domba barbados cross (DBC), 41 sampel domba komposit garut (DKG), 20 sampel domba ekor gemuk (DEG), dan 18 sampel domba ekor tipis (DET). Karakteristik karkas dan sifat perlemakan diukur dari domba jantan berumur 10-12 bulan. Identifikasi keragaman DGAT1|ALuI dianalisis dengan metode PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism). Hasil keragaman gen DGAT1 bersifat polimorfik dalam DET dan DEG, sedangkan DCA, DBC, dan DKG bersifat monomorfik. Dua genotipe disebut CC dan  CT ditemukan dalam DET dan DEG. Titik mutasi gen DGAT1 berasosiasi (P<0.05) dengan karakteristik karkas, yaitu bobot dan panjang karkas. Selain itu, keragaman gen DGAT1 juga berasosiasi signifikan (P<0.05) dengan asam lemak jenuh, yaitu asam stearat (C18:0) dan asam arakidat (C20:0) dan asam lemak tak jenuh tunggal, yaitu asam oleat (C18:1n9c). Gen DGAT1 memiliki kontribusi dalam karakteristik karkas dan komposisi asam lemak pada domba.Kata Kunci: domba, gen DGAT1, karakteristik karkas, PCR-RFLP, sifat perlemakan                                                              ABSTRACT            Characteristic of carcass and fatness traits of sheep is regulated by many genes such as DGAT1 (Diacylglycerol Acyltransferasel 1) gene. The research was aimed to investigate SNP (Single Nucleotide Polymorphism) of DGAT1 and its association with characteristic of carcass and fatness traits in Indonesian sheep. A total sample of sheeps used 150 rams of 10–12 months consisted 35 samples of compas agrinak sheep (CAS), 36 of barbados cross (BCS), 41 of garut composite (GCS), 20  of javanese fat tailed (JFT), and 18 of javanese thin tailed (JTT). Identification variant of DGAT1|ALuI were performed by PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism). The results of polymorphism of DGAT1 were found in JTT and JFT. However, SNP of DGAT1 in CAS, BCS and GCS were monomorfic. Two genotype namely CC and CT were found in JTT and JFT populations. A SNP of the DGAT1 was associated (P<0.05) with characteristic of carcass, including weight and length of carcass. The variant of DGAT1 was associated too with saturated fatty acids (SFA) including stearic acid (C18:0) and arachidic acid (C20:0), and mono unsaturated fatty acid (MUFA) including oleic acid (C18:1n9c). The DGAT1 gene was contribute to characteristic carcass and fatty acid composition in sheep.Keywords: DGAT1 gene, characteristic carcass, fatness traits, PCR-RFLP, sheep

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