Background/aim.-Screening for AAT deficiency in the child population, before the age of adquisition of smoking habits, would allow the adoption of preventive measures against pulmonary complications frequently involved. The aim of this study is to compare the efficacy of 3 different methods applied to the molecular detection of the more frequent deficient variants (S and Z) in the AAT gene, from dried blood spots.

Subjects/Interventions.-The M, S and Z variants of the AAT gene have been investigated in DNA obtained from 50 subjects with known phenotype for this enzyme as determined by isoelectric focusing. The following methods were used for genotype determination: 1) Hybridization with allele-specific oligonucleotides (ASO); 2) Amplification refractory mutation system (ARMS); 3) Polymerase chain reaction (PCR)-mediated site-directed mutagenesis.

Results: Total correspondece was found between genotype investigated by PCR-mediated site-directed mutagenesis and phenotype determined by isoelectric focusing, In the 50 subjects. However, the other methods studied were not found to be adequate as screening procedures, since the ASO method is subjected to qualitative interpretation and the ARMS requires critical conditions which are not easily replicable.

Conclusions: PCR-mediated site-directed mutagenesis is an efficient and feasible procedure for screening of AAT deficiency, and could be applied to the child population, thus facilitating the adoption of preventive measures.