PCR-Free Methodology for Detection of Single-Nucleotide Polymorphism with a Cationic Polythiophene Reporter

This study presents a nonamplification-based nucleic acid assay for the detection of single-nucleotide polymorphism (SNP) associated with familial Mediterranean fever (FMF) besides polymerase chain reaction (PCR)-based methodologies. The major objective is to show the potential of the proposed assay for rapid screening of FMF in a Mediterranean region of 400 million population. The assay relies on binding difference of specially designed wild and mutant primers to the target genomic DNA, followed by determination of unbound primers by quick titration of a cationic polythiophene reporter. The fluorescent reporter exhibits signal transition from 525 to 580 nm in the presence of unbound primers, and it correlates the binding affinity of label-free primers to the homozygous wild and mutant genomes. As a proof of concept, 26 real samples are studied relying on the ON and OFF fluorescence signals of the cationic polythiophene reporter. The results are analyzed by principal component analysis (PCA), which provides clear separation of healthy and patient individuals. The further analysis by support vector machine (SVM) classification has revealed that our assay converges to 96% overall accuracy. These results support that the PCR-free nucleic acid assay has a significant potential for rapid and cost-effective screening of familial Mediterranean fever.