Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular Lymphoma

Objective: Determination of absolute DNA concentration by Real-Time PCR is mandatory for an accurate molecular diagnosis. The critical step is a precise and reliable calibration curve. Plasmid DNA containing cloned target sequences is widely used as standards in quantitative PCR. Usually, the initia...

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Main Authors: R. Di Francia, R. De Filippi, S. Crisci, G. Iaccarino, O. Catapano, E. Varriale, F. Frigeri, A. Pinto
Format: Article
Language:English
Published: Verduci Editore 2021-05-01
Series:World Cancer Research Journal
Subjects:
Online Access:https://www.wcrj.net/wp-content/uploads/sites/5/2022/03/e1969.pdf
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author R. Di Francia
R. De Filippi
S. Crisci
G. Iaccarino
O. Catapano
E. Varriale
F. Frigeri
A. Pinto
author_facet R. Di Francia
R. De Filippi
S. Crisci
G. Iaccarino
O. Catapano
E. Varriale
F. Frigeri
A. Pinto
author_sort R. Di Francia
collection DOAJ
description Objective: Determination of absolute DNA concentration by Real-Time PCR is mandatory for an accurate molecular diagnosis. The critical step is a precise and reliable calibration curve. Plasmid DNA containing cloned target sequences is widely used as standards in quantitative PCR. Usually, the initial molecular number of plasmid molecules is deduced by theoretical calculation and this can be severely limiting the accuracy of PCR assay. Materials and Methods: We have developed a simple method to generate a precise standard curve made of plasmid DNA by competitive PCR approach. The procedure is the following: i) construction of competitor fragment; ii) generation of the stock standard by cloning the DNA target template in the plasmid vector; iii) determination of the number of molecules in the stock standard by competitive PCR; iv) analytical validation of standard curve, in terms of accuracy, sensitivity and specificity. We have used this procedure to quantify the genetic marker breakpoint, the t(14;18), associated to Follicular Lymphoma (FL) of Non-Hodgkin’s Lymphomas (NHL). Results: We found that the assessment of plasmid copy number, obtained by theoretical calculation, is overestimated compared to our competitive PCR approach (error of 22% +/-5). The standard plasmid DNA, used to generate the calibration curve, is stable and produces a high reproducible curve even after a long-term storage compared to genomic DNA curve. Conclusions: The described procedure: i) generates robust standard curves for absolute quantification of any DNA target of interest; ii) is suitable with any molecular diagnostic platform; iii) contributes significantly to improve the accuracy of routine laboratory applications.
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spelling doaj.art-993f0e86e5fb4344a70413d15c3dc45b2022-12-21T21:48:23ZengVerduci EditoreWorld Cancer Research Journal2372-34162021-05-01810.32113/wcrj_20215_19691969Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular LymphomaR. Di Francia0R. De Filippi1S. Crisci2G. Iaccarino3O. Catapano4E. Varriale5F. Frigeri6A. Pinto7Italian Association of Pharmacogenomics and Molecular Diagnostics, Ancona, ItalyDepartment of Clinical Medicine and Surgery, Federico II University, Naples, ItalyHematology-Oncology and Stem Cell Transplantation Unit, Istituto Nazionale Tumori, Fondazione “G. Pascale” IRCCS, Naples, ItalyHematology-Oncology and Stem Cell Transplantation Unit, Istituto Nazionale Tumori, Fondazione “G. Pascale” IRCCS, Naples, ItalyItalian Association of Pharmacogenomics and Molecular Diagnostics, Ancona, ItalyUOS Oncologia, Ospedale Fatebenefratelli, Naples, ItalyUOC Onco-Hematology, AORN SS Anna e Sebastiano, Caserta, ItalyHematology-Oncology and Stem Cell Transplantation Unit, Istituto Nazionale Tumori, Fondazione “G. Pascale” IRCCS, Naples, ItalyObjective: Determination of absolute DNA concentration by Real-Time PCR is mandatory for an accurate molecular diagnosis. The critical step is a precise and reliable calibration curve. Plasmid DNA containing cloned target sequences is widely used as standards in quantitative PCR. Usually, the initial molecular number of plasmid molecules is deduced by theoretical calculation and this can be severely limiting the accuracy of PCR assay. Materials and Methods: We have developed a simple method to generate a precise standard curve made of plasmid DNA by competitive PCR approach. The procedure is the following: i) construction of competitor fragment; ii) generation of the stock standard by cloning the DNA target template in the plasmid vector; iii) determination of the number of molecules in the stock standard by competitive PCR; iv) analytical validation of standard curve, in terms of accuracy, sensitivity and specificity. We have used this procedure to quantify the genetic marker breakpoint, the t(14;18), associated to Follicular Lymphoma (FL) of Non-Hodgkin’s Lymphomas (NHL). Results: We found that the assessment of plasmid copy number, obtained by theoretical calculation, is overestimated compared to our competitive PCR approach (error of 22% +/-5). The standard plasmid DNA, used to generate the calibration curve, is stable and produces a high reproducible curve even after a long-term storage compared to genomic DNA curve. Conclusions: The described procedure: i) generates robust standard curves for absolute quantification of any DNA target of interest; ii) is suitable with any molecular diagnostic platform; iii) contributes significantly to improve the accuracy of routine laboratory applications.https://www.wcrj.net/wp-content/uploads/sites/5/2022/03/e1969.pdfmolecular diagnosticsstandard curvecompetitive-pcrt(14;18)bcl2/igh major breakpoint region
spellingShingle R. Di Francia
R. De Filippi
S. Crisci
G. Iaccarino
O. Catapano
E. Varriale
F. Frigeri
A. Pinto
Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular Lymphoma
World Cancer Research Journal
molecular diagnostics
standard curve
competitive-pcr
t(14;18)bcl2/igh major breakpoint region
title Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular Lymphoma
title_full Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular Lymphoma
title_fullStr Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular Lymphoma
title_full_unstemmed Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular Lymphoma
title_short Generation of precise calibration curve for absolute quantification of DNA target by Real-Time PCR. A method for accurate molecular monitoring of t(14;18)-bearing cells in Follicular Lymphoma
title_sort generation of precise calibration curve for absolute quantification of dna target by real time pcr a method for accurate molecular monitoring of t 14 18 bearing cells in follicular lymphoma
topic molecular diagnostics
standard curve
competitive-pcr
t(14;18)bcl2/igh major breakpoint region
url https://www.wcrj.net/wp-content/uploads/sites/5/2022/03/e1969.pdf
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