RT Journal Article SR Electronic T1 Association of less common cystic fibrosis mutations with a mild phenotype. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 34 OP 37 DO 10.1136/jmg.28.1.34 VO 28 IS 1 A1 A Curtis A1 R Nelson A1 M Porteous A1 J Burn A1 S S Bhattacharya YR 1991 UL http://jmg.bmj.com/content/28/1/34.abstract AB A majority of cystic fibrosis (CF) genes (70 to 75%) share a single mutation, but the remaining 25 to 30% of defects are accounted for by more than 20 different mutations. One of the less frequent mutations, G551D, has been identified in the CF genes of two sibs and one unrelated adult patient. The adult patient also has a second rare mutation, delta I507. All three subjects exhibit a less severe phenotype than that normally associated with CF. This supports a hypothesis that the common mutation (delta F508) is responsible for the severe form of the disorder, and the minority of patients with a milder form tend to have mutations at other sites in the CF gene.