Association of improved pulmonary phenotype in Irish cystic fibrosis patients with a 3' enhancer polymorphism in alpha-1-antitrypsin.

Modifier genes other than CFTR are thought to influence lung disease phenotype in cystic fibrosis (CF). In this study, we investigated the relationship between a polymorphism (1237 G --> A) in the 3' enhancer region of the alpha-1-antitrypsin (AAT) gene and pulmonary disease severity in 320 CF patients recruited from two independent adult referral centers in Ireland, and evaluated the in vivo effect of the polymorphism on AAT levels during acute infection. When corrected for confounding variables, the polymorphism was found to make a small but significant contribution to variance in percent predicted forced expired volume in 1 sec (FEV1) (1.