Interaction was examined between smoking and each of four factors previously found to be related to AO: alpha-1 antitrypsin (PiZ allele), ABO blood groups (A antigen), ABH non-secretor status, and first degree relationship to a COPD or lung cancer patient.
The presence of the alpha(1)-antitrypsin MZ genotype may in certain circumstances produce marked aggravation of airway obstruction in individuals prone to develop COPD.