A positive, linear and significant relationship between AAT levels and EIA was observed in all groups (r = 0.83, p = 0.006 for untreated Pi*ZZ; r = 0.89, p < 0.001 for treated Pi*ZZ and r = 0.58, p < 0.001 for non-AATD related COPD patients) (Fig 1). The gene discussed is SERPINA1; the disease is chronic obstructive pulmonary disease.