Detecting Alpha-1Antitrypsin Gene Mutation Of342Gluâ†'Lys Using A Base-quenched Probe

Objective: We developed a new method of the base-quenched probe technique todetect a mutation of the alpha1-antitrypsin gene, consisting of the substitution of lysine forglutamate at342(Glu342Lys).Methods:(1). Methodology: according to the principles of probe design,6-carboxyfluorescent was directly conjugated to the3’end of the probe. Two vectors,representing the two genotypes, wild type (342Glu/Glu) and PiZZ homozygote(342Lys/Lys), were constructed as amplification templates for the methodology established.Three hundred thirty-eight patients were subjected in the present study. The genotyping ofall samples was determined by real-time polymerase chain reaction and analyzed fordifferences of the genotypes by melting curves.(2). Optimization methodology: PCRreaction condition was optimized. Finally, the sensitivity of the method was detected andthe genotyping results were verified by DNA sequencing.Results: The present data showed that the melting valleys of PiZZ homozygote andwild genotype were at41.38±0.90°C,48.64±1.33°C, respectively, and the heterozygoteshowed two melting valleys. Also, the melting valleys of all338patients were at48.64±1.33°C, which corresponding to wild genotype, hence constituting wild-typesamples (342Glu/Glu). The sensitivity analysis indicated the103copies of template DNAhad a more clear melting valley. The kappa test showed a complete concordance betweenDNA sequencing and the base-quenched probe method(K=1，P=0.000).Conclusion: This method used is precise, simple, and economic, so it is suitable forlarge-scale genotyping studies and clinical test for alpha1-antitrypsin gene mutation(Glu342Lys) in human subjects.