scholarly journals Newborn Blood Spot Screening Test Using Multiplexed Real-Time PCR to Simultaneously Screen for Spinal Muscular Atrophy and Severe Combined Immunodeficiency

2015 ◽  
Vol 61 (2) ◽  
pp. 412-419 ◽  
Author(s):  
Jennifer L Taylor ◽  
Francis K Lee ◽  
Golriz Khadem Yazdanpanah ◽  
John F Staropoli ◽  
Mei Liu ◽  
...  
Keyword(s):  
T Cell ◽  
Motor Neuron ◽  
Real Time ◽  
Real Time Pcr ◽  
Muscular Atrophy ◽  
Severe Combined Immunodeficiency ◽  
Combined Immunodeficiency ◽  
Smn1 Gene ◽  
Trec Assay ◽  
Blood Spot

Abstract BACKGROUND Spinal muscular atrophy (SMA) is a motor neuron disorder caused by the absence of a functional survival of motor neuron 1, telomeric (SMN1) gene. Type I SMA, a lethal disease of infancy, accounts for the majority of cases. Newborn blood spot screening (NBS) to detect severe combined immunodeficiency (SCID) has been implemented in public health laboratories in the last 5 years. SCID detection is based on real-time PCR assays to measure T-cell receptor excision circles (TREC), a byproduct of T-cell development. We modified a multiplexed real-time PCR TREC assay to simultaneously determine the presence or absence of the SMN1 gene from a dried blood spot (DBS) punch in a single reaction well. METHOD An SMN1 assay using a locked nucleic acid probe was initially developed with cell culture and umbilical cord blood (UCB) DNA extracts, and then integrated into the TREC assay. DBS punches were placed in 96-well arrays, washed, and amplified directly using reagents specific for TREC, a reference gene [ribonuclease P/MRP 30kDa subunit (RPP30)], and the SMN1 gene. The assay was tested on DBS made from UCB units and from peripheral blood samples of SMA-affected individuals and their family members. RESULTS DBS made from SMA-affected individuals showed no SMN1-specific amplification, whereas DBS made from all unaffected carriers and UCB showed SMN1 amplification above a well-defined threshold. TREC and RPP30 content in all DBS were within the age-adjusted expected range. CONCLUSIONS SMA caused by the absence of SMN1 can be detected from the same DBS punch used to screen newborns for SCID.

scholarly journals High-Throughput Multiplexed T-Cell–Receptor Excision Circle Quantitative PCR Assay with Internal Controls for Detection of Severe Combined Immunodeficiency in Population-Based Newborn Screening

2010 ◽  
Vol 56 (9) ◽  
pp. 1466-1474 ◽  
Author(s):  
Jacalyn L Gerstel-Thompson ◽  
Jonathan F Wilkey ◽  
Jennifer C Baptiste ◽  
Jennifer S Navas ◽  
Sung-Yun Pai ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Newborn Screening ◽  
T Cell Receptor ◽  
Severe Combined Immunodeficiency ◽  
Cell Receptor ◽  
Population Based ◽  
Combined Immunodeficiency ◽  
Clinical Validity ◽  
Trec Assay ◽  
Blood Spot

BACKGROUND Real-time quantitative PCR (qPCR) targeting a specific marker of functional T cells, the T-cell–receptor excision circle (TREC), detects the absence of functional T cells and has a demonstrated clinical validity for detecting severe combined immunodeficiency (SCID) in infants. There is need for a qPCR TREC assay with an internal control to monitor DNA quality and the relative cellular content of the particular dried blood spot punch sampled in each reaction. The utility of the qPCR TREC assay would also be far improved if more tests could be performed on the same newborn screening sample. METHODS We approached the multiplexing of qPCR for TREC by attenuating the reaction for the reference gene, with focus on maintaining tight quality assurance for reproducible slopes and for prevention of sample-to-sample cross contamination. Statewide newborn screening for SCID using the multiplexed assay was implemented, and quality-assurance data were recorded. RESULTS The multiplex qPCR TREC assay showed nearly 100% amplification efficiency for each of the TREC and reference sequences, clinical validity for multiple forms of SCID, and an analytic limit of detection consistent with prevention of contamination. The eluate and residual ghost from a 3.2-mm dried blood spot could be used as source material for multiplexed immunoassays and multiplexed DNA tests (Multiplex Plus), with no disruption to the multiplex TREC qPCR. CONCLUSIONS Population-based SCID newborn screening programs should consider multiplexing for quality assurance purposes. Potential benefits of using Multiplex Plus include the ability to perform multianalyte profiling.

scholarly journals A Multiplex Immunoassay Using the Guthrie Specimen to Detect T-Cell Deficiencies Including Severe Combined Immunodeficiency Disease

2010 ◽  
Vol 56 (9) ◽  
pp. 1460-1465 ◽  
Author(s):  
David K Janik ◽  
Barbara Lindau-Shepard ◽  
Anne Marie Comeau ◽  
Kenneth A Pass
Keyword(s):  
T Cell ◽  
Newborn Screening ◽  
Clinical Status ◽  
Severe Combined Immunodeficiency ◽  
Cross Reactivity ◽  
Multiplex Assay ◽  
Molecular Technique ◽  
Combined Immunodeficiency ◽  
Pilot Studies ◽  
Trec Assay

BACKGROUND Severe combined immunodeficiency (SCID) fulfills many of the requirements for addition to a newborn screening panel. Two newborn screening SCID pilot studies are now underway using the T-cell receptor excision circle (TREC) assay, a molecular technique. Here we describe an immunoassay with CD3 as a marker for T cells and CD45 as a marker for total leukocytes that can be used with the Guthrie specimen. METHODS The multiplexing capabilities of the Luminex platform were used. Antibody pairs were used to capture and detect CD3 and CD45 from a single 3-mm punch of the Guthrie specimen. The assay for each biomarker was developed separately in identical buffers and then combined to create a multiplex assay. RESULTS Using calibrators made from known amounts of leukocytes, a detection limit of 0.25 × 106 cells/mL for CD3 and 0.125 × 106 cells/mL for CD45 was obtained. Affinity tests showed no cross-reactivity between the antibodies to CD3 and CD45. The multiplex assay was validated against 8 coded specimens of known clinical status and linked to results from the TREC assay that had identified them. All were correctly identified by the CD345 assay. CONCLUSIONS The performance parameters of the CD345 assay met the performance characteristics generally accepted for immunoassays. Our assay classifications of positive specimens concur with previous TREC results. This CD345 assay warrants evaluation as a viable alternative or complement to the TREC assay as a primary screening tool for detecting T-cell immunodeficiencies, including SCID, in Guthrie specimens.

scholarly journals Newborn Screening for Severe Combined Immunodeficiency Using the Multiple of the Median Values of T-Cell Receptor Excision Circles

2021 ◽  
Vol 7 (3) ◽  
pp. 43
Author(s):  
Michael F. Cogley ◽  
Amy E. Wiberley-Bradford ◽  
Sean T. Mochal ◽  
Sandra J. Dawe ◽  
Zachary D. Piro ◽  
...  
Keyword(s):  
T Cell ◽  
Newborn Screening ◽  
T Cell Receptor ◽  
Severe Combined Immunodeficiency ◽  
Cell Receptor ◽  
Combined Immunodeficiency ◽  
Individual Test ◽  
Copy Numbers ◽  
Excision Circles ◽  
Trec Assay

All newborn screening programs screen for severe combined immunodeficiency by measurement of T-cell receptor excision circles (TRECs). Herein, we report our experience of reporting TREC assay results as multiple of the median (MoM) rather than using conventional copy numbers. This modification simplifies the assay by eliminating the need for standards with known TREC copy numbers. Furthermore, since MoM is a measure of how far an individual test result deviates from the median, it allows normalization of TREC assay data from different laboratories, so that individual test results can be compared regardless of the particular method, assay, or reagents used.

scholarly journals Copy Number Assessment of SMN1 Based on Real-Time PCR With High-Resolution Melting: Fast and Highly Reliable Testing

2021 ◽  
Author(s):  
Ying Xu ◽  
Tingting Song ◽  
Xiaozhou Wang ◽  
Jiao Zheng ◽  
Yu Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Real Time Pcr ◽  
Copy Number ◽  
Large Scale ◽  
High Resolution Melting ◽  
Muscular Atrophy ◽  
Survival Motor Neuron ◽  
Smn1 Gene ◽  
Gene Exon

Abstract Background: Spinal muscular atrophy (SMA) is a common neuromuscular disorder, caused by absence of both copies of the survival motor neuron 1 (SMN1) gene. Population-wide SMA screening to quantify copy number of SMN1 is recommended by multiple regions. SMN1 diagnostic assay with simplified procedure, high sensitivity and throughput is still needed.Methods: Real-Time PCR with High-Resolution Melting for the quantification of the SMN1 gene exon 7 copies and SMN1 gene exon 8 copies was established and confirmed by multiplex ligation-dependent probe amplification (MLPA). The diagnosis of 2563 individuals including SMA patients, suspected cases and the general population were analyzed by the real-time PCR. The results were compared with the gold standard test MPLA. Results: In this study, the homozygous deletions, heterozygous deletions were identified by Real-Time PCR with High-Resolution Melting method with an incidence of 10.18% and 2.42%, respectively. In addition, the R value distribution (P>0.05) among the 8 replicates and the coefficient of variation (CV<0.003) suggested that the qPCR screening test had high reproducibility. High concordance was obtained between Real-Time PCR with High-Resolution Melting and MPLA. Conclusions: The qPCR based on High-Resolution Melting provides a sensitive and high-throughput approach to large-scale SMA carrier screening with low cost and labor.

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