Loop-mediated isothermal amplification (LAMP)-based method for detecting factor V Leiden and factor II G20210A common variants.

Automated methodologies allowing for rapid detection of Factor V Leiden and Factor II G20210A variants are desirable, due to a high number of tested patients. Here, we report a preliminary validation of a CE-marked in vitro diagnostic (IVD) certified method for simultaneous detection of Factor V Leiden and Factor II G20210A variants on whole blood samples. The novel method is based on Loop-mediated isothermal AMPlification (LAMP) applied for a duplex detection of Factor V Leiden and Factor II G20210A variants without requiring prior DNA extraction, whereas the routine one is a TaqMan SNP genotyping targeting genomic DNA. We tested routine patients for both variants using novel and current methods and estimated concordance rate. Patients were tested under similar laboratory procedures. One hundred and eight patients referred for the thrombophilia testing in the period between 9th December 2019 to 27th February 2020 represented the study population. We routinely identified for the Factor V Leiden variant 163 wild-type, 17 heterozygotes and no homozygote. Concerning the Factor II G20210A variant, we identified 170 wild-type, nine heterozygotes and one homozygous carrier. Two heterozygotes carried both variants (double heterozygotes). The LAMP method showed a 100% concordance rate, detecting rightly all genotypes. The LAMP for a duplex detection of common thrombophilia variants shows analytic performances as good as those of the standard method.

Genotyping on blood and buccal cells using loop-mediated isothermal amplification in healthy humans.

Genetic variations contribute to phenotypic individual vulnerabilities to sleep debt, particularly for five single nucleotide polymorphisms (SNPs). Loop-mediated isothermal amplification and melting curve analysis (LAMP-MC) is a recently developed method to characterize SNPs. The aim of present study was to evaluate the LAMP-MC method on blood and buccal cells for detection of five SNPs of interest in healthy humans. We first analyzed signals obtained from LAMP-MC method on 42 samples. Then we compared the results with those of referent TaqMan method. The LAMP-MC method produced specific melting curves for the five SNPs. A high concordance of genotyping results was observed between the two methods for rs5751876_ADORA2A, rs1800629_TNF-α, rs73598374_ADA and rs228697_PER3 in blood and saliva (Cohen's kappa coefficient >0.80). A good agreement ( = 0.61) was observed for rs4680_COMT in blood only. LAMP-MC is a simple and reliable method to study genetic influences on health, sleep debt-related performance impairments and countermeasures.

Diphtheria in Belgium: 2010-2017.

In Western Europe, the incidence of both respiratory and cutaneous diphtheria, caused by toxin-producing Corynebacterium diphtheriae, Corynebacterium ulcerans or Corynebacterium pseudotuberculosis, has been low over the past few decades thanks to the use of an effective vaccine and a high level of vaccination coverage. However, the disease has still not been eradicated and continues to occur in all of Europe. In order to prevent sequelae or a fatal outcome, diphtheria antitoxin (DAT) should be administered to suspected diphtheria patients as soon as possible, but economic factors and issues concerning regulations have led to poor availability of DAT in many countries. The European Centre for Disease Prevention and Control and World Health Organization have called for European Union-wide solutions to this DAT-shortage. In order to illustrate the importance of these efforts and underline the need for continued diphtheria surveillance, we present data on all registered cases of toxigenic and non-toxigenic C. diphtheriae, C. ulcerans and C. pseudotuberculosis in Belgium during the past decade, up to and including 2017.

Lactase persistence genotyping on whole blood by loop-mediated isothermal amplification and melting curve analysis.

BACKGROUND: The lactase persistence phenotype is controlled by a regulatory enhancer region upstream of the Lactase (LCT) gene. In northern Europe, specifically the -13910C > T variant has been associated with lactase persistence whereas other persistence variants, e.g. -13907C > G and -13915 T > G, have been identified in Africa and the Middle East. The aim of the present study was to compare a previously developed high resolution melting assay (HRM) with a novel method based on loop-mediated isothermal amplification and melting curve analysis (LAMP-MC) with both whole blood and DNA as input material. METHODS: To evaluate the LAMP-MC method, we used 100 whole blood samples and 93 DNA samples in a two tiered study. First, we studied the ability of the LAMP-MC method to produce specific melting curves for several variants of the LCT enhancer region. Next, we performed a blinded comparison between the LAMP-MC method and our existing HRM method with clinical samples of unknown genotype. RESULTS: The LAMP-MC method produced specific melting curves for the variants at position -13909, -13910, -13913 whereas the -13907C > G and -13915 T > G variants produced indistinguishable melting profiles. CONCLUSION: The LAMP-MC assay is a simple method for lactase persistence genotyping and compares well with our existing HRM method.

Improving specificity of Bordetella pertussis detection using a four target real-time PCR.

The incidence of whooping cough, a contagious respiratory disease caused by Bordetella pertussis, is on the rise despite existing vaccination programmes. Similar, though usually milder, respiratory symptoms may be caused by other members of the Bordetella genus: B. parapertussis, B. holmesii, and B. bronchiseptica. Pertussis diagnosis is mostly done using PCR, but the use of multiple targets is necessary in order to differentiate the different Bordetella spp. with sufficient sensitivity and specificity. In this study we evaluate a multiplex PCR assay for the differentiation of B. pertussis from other Bordetella spp., using the targets IS481, IS1001, IS1002, and recA. Moreover, we retrospectively explore the epidemiology of Bordetella spp. infections in Belgium, using the aforementioned assay over a three-year period, from 2013 until 2015.