Genotyping of folate metabolism genes
is of great importance in
disease diagnosis and prevention. However, most current detection
methods used for folate metabolism gene genotyping are based on sequencing
and chips, which suffer from a high cost and laborious and time-consuming
procedures. Herein, we reported a multiplex asymmetric PCR-HRM strategy
for identifying genotypes of folate metabolism genes in a single tube.
The proposed multiplex PCR-HRM assay has been successfully applied
to identify the genotypes of folate metabolism genes, methylene tetrahydrofolate
reductase (C677T, A1298C) and methionine synthase reductase A66G,
on 1 μL of genomic DNA (gDNA) samples directly released from
blood specimens, and the genotyping results were 100% consistent with
the results of sequencing. The assay allows us to accurately detect
the genotypes of gDNA with the detection limit down to 1 ng, which
meets the clinical requirement. What is more, the capacity of resistance
to aerosol pollution of the multiplex asymmetric PCR-HRM biosensing
was first addressed and has been evaluated as it can withstand contamination
of roughly 12.5–25% interfering nucleic acids. Because of the
advantages of multiplex detection, high accuracy, and resistance to
aerosol pollution and having no open tube procedure, this approach
would pave the way for establishing a fast and cost-effective platform
for folate metabolism gene genotyping and other SNP genotyping in
clinical diagnostics.
Loop-mediated
isothermal amplification (LAMP) is a commonly used
alternative to PCR for point-of-care detection of nucleic acids due
to its rapidity, sensitivity, specificity, and simpler instrumentation.
While dual-labeled TaqMan probes are widely used in PCR for single-nucleotide
polymorphism (SNP) genotyping, real-time LAMP primarily relies on
turbidimetry or intercalator fluorescence measurements, which can
be non-specific and generate false-positive results. In this study,
we propose a closed-tube, dual-labeled RNA-modified probes and RNase
H II-assisted real-time LAMP (RART-LAMP) method for SNP genotyping.
Our findings indicate that (1) fluorescence signals were predominantly
derived from probe hydrolysis rather than hybridization, (2) temperature-controlled
hybridization between the probe and template ensured the specificity
of SNP analysis, and (3) RNase H II hydrolysis between the target
containing SNP sites and probes did not exhibit sequence specificity.
Our RART-LAMP approach demonstrated excellent performance in genotyping
C677T clinical samples, including gDNA extracted from blood, saliva,
and swabs. More importantly, saliva and swab samples could be directly
analyzed without any pretreatment, indicating promising prospects
for nucleic acid analysis at the point of care in resource-limited
settings.
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