Rapid PCR real-time genotyping of M-Malton alpha1-antitrypsin deficiency alleles by molecular beacons

Alpha1-Antitrypsin deficiency is an autosomal codominant inherited disorder, with increased risk of developing lung and liver disease. The large majority of subjects affected by alpha1-antitrypsin deficiency carry the PIZZ or PISZ genotypes, which can be easily detected using several molecular methods. Another pathologic allele, the M-Malton variant (also known as Mnichinan and Mcagliari), can mimic the Pi Z clinical phenotype, but this alpha1-antitrypsin deficiency variant is not easily recognizable and, therefore, seems to be more under-recognized than the Z or S alleles. We report the development of a rapid qualitative fluorescent real-time PCR assay designed for the detection of the M-Malton alpha1-antitrypsin deficiency alleles using 2 specific molecular beacons. The assay is able to detect in a single tube the homozygous as well the heterozygous genotypes. The procedure combines the great sensitivity of the polymerase chain reaction, the specificity provided by allele-specific molecular beacons, and the throughput of a multi-color fluorescence detection procedure. This technique will be useful for research and molecular diagnostic laboratories involved in the study of alpha1-antitrypsin deficiency-related diseases.