for the Gene Modifier Study Group C YSTIC FIBROSIS (CF) IS A REcessive monogenic disorder characterizedbymultiorganinvolvement and clinical heterogeneity that is incompletely explained by mutations within the cystic fibrosis transmembraneconductanceregulator(CFTR) gene (OMIM 602421). 1 Patients with CF, including those homozygous for DF508, smallfraction(Ϸ3%-5%)ofpatientswith CF develops severe liver disease characterized by cirrhosis with portal hypertension (CFLD) 1 ; thus, non-CFTR genetic variability may contribute to risk for severe liver disease. [14][15][16][17] To determine the association between non-CFTR genetic polymorphisms and CFLD, we studied 9 functional variants in 5 genes previously See also Patient Page.