Introduction: more than 100 alleles have been described on the alpha 1 antitrypsin gene. Normal variants (PiM1, PiM2 and PiM3) encodes AAT molecules which are different but functional and normally secreted. The more frequent risk variants are PiS and PiZ. In this study, an AAT polymorphism analysis in correlation with pulmonary diseases was conducted.
Material and methods: analyses were performed on 96 asthmatics, 67 emphysema cases and 318 control subjects. Alpha 1 antitrypsin phenotypes were studied by quantitative determination of AAT concentration and isoelectrofocusing. Genotyping was performed by RFLP PCR.
Results: PiM1, PiM2, PiM3, PiS and PiZ allelic frequencies were calculated (0.7395, 0.2291, 0.0156, 0.0104, 0.0052 in asthmatics; 0.7547, 0.1716, 0.0298, 0.0298, 0.0149 in emphysema patients and 0.8030, 0.1525, 0.0408, 0.006, 0.0000 in controls, respectively). Results showed an increase in PiM2 allele frequencies in both patients' groups compared to controls. Allelic frequencies difference is significant only with the asthmatic group (p=0,0179). PiS and PiZ deficiency alleles are more prevalent in the emphysema (0.0298, 0.0149) than in the asthmatic subjects (0.0104, 0.0052). Meanwhile, no significant difference in PiS and PiZ allelic frequencies was observed between patients and controls.
Conclusion: PiM2 allele can be considered as genetic risk factor for asthma. PiS and PiZ alleles are very rare in Tunisia in comparison with the European population, leading to a very small contribution in pulmonary diseases pathogenesis in Tunisia.