A high-throughput protocol for mutation scanning of the BRCA1 and BRCA2 genes

A High-Resolution Melting Analysis with an Unlabeled Probe for CRISPR/Cas9-Induced ZBED6 Knockout Pigs Detection

BACKGROUND

The zinc finger BED-type containing six knockout (ZBED6-KO) pigs were created to improve economic traits by increasing the expression of insulin-like growth factor 2. They were generated by CRISPR/CRISPR-associated protein 9 (Cas9) technology and a single-base deletion of ZBED6 was found. An efficient and rapid method was needed to detect this type of pig.

OBJECTIVE

This study aimed to develop a high-resolution melting (HRM) method to detect ZBED6-KO pigs.

METHODS

An unlabeled probe and two primers were designed to develop the HRM method. The limit of detection, specificity, and accuracy of the established method were tested by the constructed plasmid and DNA extracts of tissue specimens.

RESULTS

The limit of detection by the established method was 102 copies/µL. The HRM method with an unlabeled probe showed good specificity and high accuracy.

CONCLUSIONS

The established HRM analysis with an unlabeled probe showed it to be a highly effective, rapid, and reliable method to distinguish ZBED6-KO pigs from wild-type pigs.

HIGHLIGHTS

It is the first time that HRM analysis with an unlabeled probe has been used in the detection of genome editing pigs by the CRISPR/Cas9 technology.

Rapid screening of UPB1 gene variations by high resolution melting curve analysis

The present study aimed to analyze gene mutations in patients with β-ureidopropinoase deficiency and establish a rapid detection method for β-ureidopropinoase (UPB1) pathogenic variations by high resolution melting (HRM) analysis. DNA samples with known UPB1 mutations in three patients with β-ureidopropinoase deficiency were utilized to establish a rapid detection method for UPB1 pathogenic variations by HRM analysis. Further rapid screening was performed on two patients diagnosed with β-ureidopropinoase deficiency and 50 healthy control individuals. The results showed that all known UPB1 gene mutations can be analyzed by a specially designed HRM assay. Each mutation has specific HRM profiles which could be used in rapid screening. The HRM method could correctly identify all genetic mutations in two children with β-ureidopropinoase deficiency. In addition, the HRM assay also recognized four unknown mutations. To conclude, the results support future studies of applying HRM analysis as a diagnostic approach for β-ureidopropinoase deficiency and a rapid screening method for UPB1 mutation carriers.

Diagnosis of genetic amyloidosis through the analysis of transthyretin gene mutation using high-resolution melting

Transthyretin amyloidosis can be either the wild-type (ATTR-wt) or the hereditary form (ATTR-m) with autosomal dominant inheritance. ATTR seems to be an underdiagnosed disease, despite now being recognized as one of the most frequent causes of heart failure (HF) with preserved ejection fraction. The confirmation of diagnosis includes a genetic analysis as a critical step to distinguish between ATTR-wt and hereditary amyloidosis. The present study aimed to evaluate the potential application of High-Resolution Melting (HRM) analysis for identifying gene mutations in patients with suspected ATTR-m. We have adapted and validated the use of HRM for TTR mutations. We, therefore, sequenced the TTR gene and used HRM in a group of 134 patients suspected of suffering from amyloidosis. Seven patients were diagnosed with mutations in the TTR gene (p.Glu74Gln, heterozygous p.Val142Ile, and homozygous p.Val142Ile). HRM is capable of clearly detecting these TTR mutations, including the heterozygous and homozygous variants. The results show a 100% correlation between the HRM study and TTR sequencing. These results support future studies of applying HRM analysis as a diagnostic approach for ATTR-m, mainly for epidemiological studies.

High-resolution melting analysis for rapid and sensitive MYD88 screening in chronic lymphocytic leukemia

High resolution melting (HRM) assay is a novel technology for the fast, high-throughput, sensitive, post-PCR analysis of genetic mutations. Myeloid differentiation primary response 88 (MYD88) mutations are frequently reported in chronic lymphocytic leukemia (CLL) and confer a worse prognosis. The objective of the present study was to assess the value of HRM analysis for the rapid screening of MYD88 mutations in patients with CLL. Genomic DNA samples were extracted from the bone marrow of 129 newly diagnosed patients with CLL. A plasmid with an MYD88-L265P mutation was constructed, and the p.L265P substitution, which is the predominant MYD88 mutation in CLL, was detected using HRM analysis and direct sequencing. The plasmid pCMV-MYD88-L265P-Mu was successfully constructed as a positive control, and was verified by direct sequencing. The normalized and shifted melting curves of 6/129 (4.65%) samples were clearly different from those of other patients by HRM analysis. In addition, the 794T>C mutation in MYD88 was identified in 6 (4.65%) patients by direct sequencing. Sensitivity evaluation revealed that the HRM assay had a higher sensitivity (to 1% dilution) than direct sequencing, in addition to being convenient and time-saving. The MYD88 p.L256P mutation has been implicated to be associated with adverse prognosis in CLL. HRM analysis has the potential to be a routine prescreening technique to identify the MYD88 p.L256P mutation and may facilitate the clinical treatment of CLL.

Monoallelic characteristic-bearing heterozygous L1053X in BRCA2 gene among Sudanese women with breast cancer

Background

Breast cancer (BC) is the most common type of cancer in women. Among many risk factors of BC, mutations in BRCA2 gene were found to be the primary cause in 5–10% of cases. The majority of deleterious mutations are frameshift or nonsense mutations. Most of the reported BRCA2 mutations are protein truncating mutations.

Methods

The study aimed to describe the pattern of mutations including single nucleotide polymorphisms (SNPs) and variants of the BRCA2 (exon11) gene among Sudanese women patients diagnosed with BC. In this study a specific region of BRCA2 exon 11 was targeted using PCR and DNA sequencing.

Results

Early onset cases 25/45 (55.6%) were premenopausal women with a mean age of 36.6 years. Multiparity was more frequent within the study amounting to 30 cases (66.6%), with a mean parity of 4.1. Ductal type tumor was the predominant type detected in 22 cases (48.8%) among the reported histotypes. A heterozygous monoallelic nonsense mutation at nucleotide 3385 was found in four patients out of 9, where TTA codon was converted into the stop codon TGA.

Conclusion

This study detected a monoallelic nonsense mutation in four Sudanese female patients diagnosed with early onset BC from different families. Further work is needed to demonstrate its usefulness in screening of BC.

Screening of WT1 mutations in exon 8 and 9 in children with steroid resistant nephrotic syndrome from a single centre and establishment of a rapid screening assay using high-resolution melting analysis in a clinical setting

BACKGROUND

Mutations in Wilm's tumor 1 (WT1) gene is one of the commonly reported genetic mutations in children with steroid resistant nephrotic syndrome (SRNS). We report the results of direct sequencing of exons 8 and 9 of WT1 gene in 100 children with SRNS from a single centre. We standardized and validated High Resolution Melt (HRM) as a rapid and cost effective screening step to identify individuals with normal sequence and distinguish it from those with a potential mutation. Since only mutation positive samples identified by HRM will be further processed for sequencing it will help in reducing the sequencing burden and speed up the screening process.

METHODS

One hundred SRNS children were screened for WT1 mutations in Exon 8 and 9 using Sanger sequencing. HRM assay was standardized and validated by performing analysis for exon 8 and 9 on 3 healthy control and 5 abnormal variants created by site directed mutagenesis and verified by sequencing. To further test the clinical applicability of the assay, we screened additional 91 samples for HRM testing and performed a blinded assessment.

RESULTS

WT1 mutations were not observed in the cohort of children with SRNS. The results of HRM analysis were concordant with the sequencing results.

CONCLUSION

The WT1 gene mutations were not observed in the SRNS cohort indicating it has a low prevalence. We propose applying this simple, rapid and cost effective assay using HRM technique as the first step for screening the WT1 gene hot spot region in a clinical setting.

Rapid detection of pathological mutations and deletions of the haemoglobin beta gene (HBB) by High Resolution Melting (HRM) analysis and Gene Ratio Analysis Copy Enumeration PCR (GRACE-PCR)

OBJECTIVES

Inherited disorders of haemoglobin are the world's most common genetic diseases, resulting in significant morbidity and mortality. The large number of mutations associated with the haemoglobin beta gene (HBB) makes gene scanning by High Resolution Melting (HRM) PCR an attractive diagnostic approach. However, existing HRM-PCR assays are not able to detect all common point mutations and have only a very limited ability to detect larger gene rearrangements. The aim of the current study was to develop a HBB assay, which can be used as a screening test in highly heterogeneous populations, for detection of both point mutations and larger gene rearrangements.

METHODS

The assay is based on a combination of conventional HRM-PCR and a novel Gene Ratio Analysis Copy Enumeration (GRACE) PCR method. HRM-PCR was extensively optimised, which included the use of an unlabelled probe and incorporation of universal bases into primers to prevent interference from common non-pathological polymorphisms. GRACE-PCR was employed to determine HBB gene copy numbers relative to a reference gene using melt curve analysis to detect rearrangements in the HBB gene. The performance of the assay was evaluated by analysing 410 samples.

RESULTS

A total of 44 distinct pathological genotypes were detected. In comparison with reference methods, the assay has a sensitivity of 100 % and a specificity of 98 %.

CONCLUSION

We have developed an assay that detects both point mutations and larger rearrangements of the HBB gene. This assay is quick, sensitive, specific and cost effective making it suitable as an initial screening test that can be used for highly heterogeneous cohorts.

Clustered somatic mutations are frequent in transcription factor binding motifs within proximal promoter regions in melanoma and other cutaneous malignancies

Most cancer DNA sequencing studies have prioritized recurrent non-synonymous coding mutations in order to identify novel cancer-related mutations. Although attention is increasingly being paid to mutations in non-coding regions, standard approaches to identifying significant mutations may not be appropriate and there has been limited analysis of mutational clusters in functionally annotated non-coding regions. We sought to identify clustered somatic mutations (hotspot regions across samples) in functionally annotated regions in melanoma and other cutaneous malignancies (cutaneous squamous cell carcinoma, basal cell carcinoma and Merkel cell carcinoma). Sliding window analyses revealed numerous recurrent clustered hotspot mutations in proximal promoters, with some specific clusters present in up to 25% of cases. Mutations in melanoma were clustered within ETS and Sp1 transcription factor binding motifs, had a UV signature and were identified in other cutaneous malignancies. Clinicopathologic correlation and mutation analysis support a causal role for chronic UV irradiation generating somatic mutations in transcription factor binding motifs of proximal promoters.

Health professionals' evaluation of delivering treatment-focused genetic testing to women newly diagnosed with breast cancer

Increasingly, women are offered genetic testing shortly after diagnosis of breast cancer to facilitate decision-making about treatment, often referred to as 'treatment-focused genetic testing' (TFGT). As understanding the attitudes of health professionals is likely to inform its integration into clinical care we surveyed professionals who participated in our TFGT randomized control study. Thirty-six completed surveys were received (response rate 59%), 15 (42%) health professionals classified as genetic and 21 (58%) as non-genetic. Mainly positive experiences with participating in the TFGT trial were reported. The high cost of testing and who could best deliver information about TGFT to the patient were raised as key constraints to implementation of TFGT in usual care. More non-genetic than genetic health professionals (44 vs 8%) preferred that the surgeon provide the information for decision-making about TFGT. While costs of TFGT itself and the time and effort of staff involved were perceived barriers, as testing costs become lower, it is expected that TFGT will become a routine part of standard clinical care for patients at high genetic risk in the near future.

High-resolution melting (HRM) assay for the detection of recurrent BRCA1/BRCA2 germline mutations in Tunisian breast/ovarian cancer families

Germline deleterious mutations in the BRCA1/BRCA2 genes are associated with an increased risk for the development of breast and ovarian cancer. Given the large size of these genes the detection of such mutations represents a considerable technical challenge. Therefore, the development of cost-effective and rapid methods to identify these mutations became a necessity. High resolution melting analysis (HRM) is a rapid and efficient technique extensively employed as high-throughput mutation scanning method. The purpose of our study was to assess the specificity and sensitivity of HRM for BRCA1 and BRCA2 genes scanning. As a first step we estimate the ability of HRM for detection mutations in a set of 21 heterozygous samples harboring 8 different known BRCA1/BRCA2 variations, all samples had been preliminarily investigated by direct sequencing, and then we performed a blinded analysis by HRM in a set of 68 further sporadic samples of unknown genotype. All tested heterozygous BRCA1/BRCA2 variants were easily identified. However the HRM assay revealed further alteration that we initially had not searched (one unclassified variant). Furthermore, sequencing confirmed all the HRM detected mutations in the set of unknown samples, including homozygous changes, indicating that in this cohort, with the optimized assays, the mutations detections sensitivity and specificity were 100 %. HRM is a simple, rapid and efficient scanning method for known and unknown BRCA1/BRCA2 germline mutations. Consequently the method will allow for the economical screening of recurrent mutations in Tunisian population.

Screening of exon 11 of BRCA1 gene using the high resolution melting approach for diagnosis in Moroccan breast cancer patients

Background

Identification of specific mutations in cancer patients may lead to the discovery of genes, which can affect susceptibility and/or prognosis. It has previously been reported that mutations in BRCA1 and BRCA2 genes are linked to breast cancer. Here, we evaluated the use of the High Resolution Melting (HRM) approach to screen for mutations in exon 11 of BRCA1 gene in Moroccan patients.

Methods

HRM analysis was used to screen exon 11 from 71 breast cancer patients in order to detect different variants. Conventional Sanger sequencing was used to confirm the presence of possible mutations. Distribution of different SNPs was determined by SNaPshot analysis software.

Results

In order to assess the efficacy of the HRM approach to screen for mutations, especially in diagnosis, we first used two samples with previously known mutations, “2924delA and 3398delC”. Indeed, these previously known sequence variants were detected by the HRM approach and yielded melting curves with atypical shape relative to wild-type control sequences. We then analyzed, 69 samples from breast cancer patients using the HRM method, and were able to detect two samples with atypical curves. Sequencing of the two samples, using the conventional Sanger approach, confirmed the presence of the same SNP (c.2612C > T) in both samples.

Conclusions

Our results strongly suggest that the HRM approach represents a reliable and highly sensitive method for mutation scanning, especially in diagnosis.

Transcriptome interrogation of human myometrium identifies differentially expressed sense-antisense pairs of protein-coding and long non-coding RNA genes in spontaneous labor at term

OBJECTIVE

To identify differentially expressed long non-coding RNA (lncRNA) genes in human myometrium in women with spontaneous labor at term.

MATERIALS AND METHODS

Myometrium was obtained from women undergoing cesarean deliveries who were not in labor (n = 19) and women in spontaneous labor at term (n = 20). RNA was extracted and profiled using an Illumina® microarray platform. We have used computational approaches to bound the extent of long non-coding RNA representation on this platform, and to identify co-differentially expressed and correlated pairs of long non-coding RNA genes and protein-coding genes sharing the same genomic loci.

RESULTS

We identified co-differential expression and correlation at two genomic loci that contain coding-lncRNA gene pairs: SOCS2-AK054607 and LMCD1-NR_024065 in women in spontaneous labor at term. This co-differential expression and correlation was validated by qRT-PCR, an experimental method completely independent of the microarray analysis. Intriguingly, one of the two lncRNA genes differentially expressed in term labor had a key genomic structure element, a splice site, that lacked evolutionary conservation beyond primates.

CONCLUSIONS

We provide, for the first time, evidence for coordinated differential expression and correlation of cis-encoded antisense lncRNAs and protein-coding genes with known as well as novel roles in pregnancy in the myometrium of women in spontaneous labor at term.

Loop nucleotide polymorphism in a putative miRNA precursor associated with seed length in rice (Oryza sativa L.)

The terminal loop region of primary miRNA transcripts is an important determinant controlling miRNA function in human, animals and plants. However, the effects of polymorphisms in loop region of miRNA precusors on phenotypic variation have not been reported, especially on agronomic traits in rice. From rice japonica variety Koshihikari and indica Guichao2, we isolated a precursor of putative miRNA osa-MIR2923a. We detected a GG/AA polymorphism in the loop structure from japonica and indica rice varieties, which was corresponding to japonica/indica rice differentiation. By using high-resolution melting (HRM) analysis, we measured the polymorphisms in a RIL (recombinant inbred lines) population derived from japonica variety Koshihikari and indica Guichao2. We found that the GG/AA polymorphism in the osa-MIR2923a loop was correlated to grain length and length-width ratio. We further found the significant association between seed length and GG/AA polymorphism in a population consisting of 72 rice landraces. Three targets were predicted, whose expressions showed significant differences between the two varieties. Our results suggested that the putative miRNA precursor and the three target genes could play functional roles for indica/japonica seed differentiation.

Symmetric snapback primers for scanning and genotyping of the cystic fibrosis transmembrane conductance regulator gene

BACKGROUND

High-resolution melting of PCR products is an efficient and analytically sensitive method to scan for sequence variation, but detected variants must still be identified. Snapback primer genotyping uses a 5' primer tail complementary to its own extension product to genotype the resulting hairpin via melting. If the 2 methods were combined to analyze the same PCR product, the residual sequencing burden could be reduced or even eliminated.

METHODS

The 27 exons and neighboring splice sites of the CFTR [cystic fibrosis transmembrane conductance regulator (ATP-binding cassette sub-family C, member 7)] gene were amplified by the PCR in 39 fragments. Primers included snapback tails for genotyping 7 common variants and the 23 CFTR mutations recommended for screening by the American College of Medical Genetics. After symmetric PCR, the amplicons were analyzed by high-resolution melting to scan for variants. Then, a 5-fold excess of H2O was added to each reaction to produce intramolecular hairpins for snapback genotyping by melting. Each melting step required <10 min. Of the 133 DNA samples analyzed, 51 were from CFTR patient samples or cell lines.

RESULTS

As expected, the analytical sensitivity of heterozygote detection in blinded studies was 100%. Snapback genotyping reduced the need for sequencing from 7.9% to 0.5% of PCR products; only 1 amplicon every 5 patients required sequencing to identify nonanticipated rare variants. We identified 2 previously unreported variants: c.3945A>G and c.4243-5C>T.

CONCLUSIONS

CFTR analysis by sequential scanning and genotyping with snapback primers is a good match for targeted clinical genetics, for which high analytical accuracy and rapid turnaround times are important.

A case of synchronous double primary breast carcinoma and osteosarcoma: Mismatch repair genes mutations as a possible cause for multiple early onset malignant tumors

Background:

Simultaneous or consequent development of multiple solid tumors might be faced in some patients, especially the young. These tumors might be related to certain hereditary cancer syndromes or certain genetic predispositions.

Case Report:

We present the case of a 19-year-old woman with metastatic breast cancer to the contralateral axillary lymph node, associated with simultaneous osteosarcoma of the left lower femur. As she did not fit into any of the familial cancer syndromes, genetic predisposition was suspected. We detected MLH1 and MSH2 promotor methylation (PM), microsatellite instability (MSI), and different mutational events in both tumors. BRCA1 gene mutations were detected in the breast tumor, with reduced mRNA expression of BRCA1&2. ERCC1, MLH1 and MSH2, especially in OS, and RRM1 was overexpressed in both tumors.

Conclusions:

Aberrations in MMR genes could explain simultaneous or consequent development of multiple solid tumors, especially in a young patient. We recommend detecting these defects, close follow-up for those patients, and genetic counseling for their family members. Further studies in a larger population are essential to support our results.

Validation of a quantitative PCR-high-resolution melting protocol for simultaneous screening of COL1A1 and COL1A2 point mutations and large rearrangements: application for diagnosis of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a connective tissue disorder mostly characterized by autosomal dominant inheritance. Over 1,100 causal mutations have been identified scattered along all exons of genes encoding type I collagen precursors, COL1A1 and COL1A2. Because of the absence of mutational hotspots, Sanger sequencing is considered the gold standard for molecular analysis even if the workload is very laborious and expensive. To overcome this issue, different prescreening methods have been proposed, including DHPLC and biochemical studies on cultured dermal fibroblasts; however, both approaches present different drawbacks. Moreover, in case of patients who screen negative for point mutations, an additional screening step for complex rearrangements is required; the added causative variants expected from this approach are about 1-2%. The aim of this study was to optimize and validate a new protocol that combines quantitative PCR (qPCR) and high-resolution melting (HRM) curve analysis to reduce time and costs for molecular diagnosis. Results of qPCR-HRM screening on 57 OI patients, validated by DHPLC-direct sequencing and multiplex ligation-dependent probe amplification (MLPA), indicate that all alterations identified with the mentioned methodologies are successfully detected by qPCR-HRM. Moreover, HRM was able to discriminate complex genotypes and homozygous variants. Finally, qPCR-HRM outperformed direct sequencing and DHPLC-MLPA in terms of rapidity and costs.

Tandem duplication of chromosomal segments is common in ovarian and breast cancer genomes

The application of paired-end next generation sequencing approaches has made it possible to systematically characterize rearrangements of the cancer genome to base-pair level. Utilizing this approach, we report the first detailed analysis of ovarian cancer rearrangements, comparing high-grade serous and clear cell cancers, and these histotypes with other solid cancers. Somatic rearrangements were systematically characterized in eight high-grade serous and five clear cell ovarian cancer genomes and we report here the identification of > 600 somatic rearrangements. Recurrent rearrangements of the transcriptional regulator gene, TSHZ3, were found in three of eight serous cases. Comparison to breast, pancreatic and prostate cancer genomes revealed that a subset of ovarian cancers share a marked tandem duplication phenotype with triple-negative breast cancers. The tandem duplication phenotype was not linked to BRCA1/2 mutation, suggesting that other common mechanisms or carcinogenic exposures are operative. High-grade serous cancers arising in women with germline BRCA1 or BRCA2 mutation showed a high frequency of small chromosomal deletions. These findings indicate that BRCA1/2 germline mutation may contribute to widespread structural change and that other undefined mechanism(s), which are potentially shared with triple-negative breast cancer, promote tandem chromosomal duplications that sculpt the ovarian cancer genome.

BRCA mutation frequency and patterns of treatment response in BRCA mutation-positive women with ovarian cancer: a report from the Australian Ovarian Cancer Study Group

PURPOSE

The frequency of BRCA1 and BRCA2 germ-line mutations in women with ovarian cancer is unclear; reports vary from 3% to 27%. The impact of germ-line mutation on response requires further investigation to understand its impact on treatment planning and clinical trial design.

PATIENTS AND METHODS

Women with nonmucinous ovarian carcinoma (n = 1,001) enrolled onto a population-based, case-control study were screened for point mutations and large deletions in both genes. Survival outcomes and responses to multiple lines of chemotherapy were assessed.

RESULTS

Germ-line mutations were found in 14.1% of patients overall, including 16.6% of serous cancer patients (high-gradeserous, 17.1%); [corrected] 44% had no reported family history of breast orovarian cancer.Patients carrying germ-line mutations had improved rates of progression-free and overall survival. In the relapse setting, patients carrying mutations more frequently responded to both platin- and nonplatin-based regimens than mutation-negative patients, even in patients with early relapse after primary treatment. Mutation-negative patients who responded to multiple cycles of platin-based treatment were more likely to carry somatic BRCA1/2 mutations.

CONCLUSION

BRCA mutation status has a major influence on survival in ovarian cancer patients and should be an additional stratification factor in clinical trials. Treatment outcomes in BRCA1/2 carriers challenge conventional definitions of platin resistance, and mutation status may be able to contribute to decision making and systemic therapy selection in the relapse setting. Our data, together with the advent of poly(ADP-ribose) polymerase inhibitor trials, supports the recommendation that germ-line BRCA1/2 testing should be offered to all women diagnosed with nonmucinous, ovarian carcinoma, regardless of family history.

The potential of TaqMan Array Cards for detection of multiple biological agents by real-time PCR

The TaqMan Array Card architecture, normally used for gene expression studies, was evaluated for its potential to detect multiple bacterial agents by real-time PCR. Ten PCR assays targeting five biological agents (Bacillus anthracis, Burkholderia mallei, Burkholderia pseudomallei, Francisella tularensis, and Yersinia pestis) were incorporated onto Array Cards. A comparison of PCR performance of each PCR in Array Card and singleplex format was conducted using DNA extracted from pure bacterial cultures. When 100 fg of agent DNA was added to Array Card channels the following levels of agent detection (where at least one agent PCR replicate returned a positive result) were observed: Y. pestis 100%, B. mallei & F. tularensis 93%; B. anthracis 71%; B. pseudomallei 43%. For B. mallei & pseudomallei detection the BPM2 PCR, which detects both species, outperformed PCR assays specific to each organism indicating identification of the respective species would not be reproducible at the 100 fg level. Near 100% levels of detection were observed when 100 fg of DNA was added to each PCR in singleplex format with singleplex PCRs also returning sporadic positives at the 10 fg per PCR level. Before evaluating the use of Array Cards for the testing of environmental and clinical sample types, with potential levels of background DNA and PCR inhibitors, users would therefore have to accept a 10-fold reduction in sensitivity of PCR assays on the Array Card format, in order to benefit for the capacity to test multiple samples for multiple agents. A two PCR per agent strategy would allow the testing of 7 samples for the presence of 11 biological agents or 3 samples for 23 biological agents per card (with negative control channels).