CHRONIC SINUSITIS AND A NEGATIVE SWEAT TEST IN A PATIENT WITH CYSTIC-FIBROSIS

The diagnosis of cystic fibrosis (CF) is based on sweat chloride and D NA mutation testing. A subset of CF patients may have normal sweat chl oride levels, thus requiring DNA analysis for confirmation of the diag nosis. These patients may escape diagnosis if sweat testing is the onl y modality used for screening. Recently, the putative structural gene for CF was localized to chromosome 7. The deIta-F508 mutation accounts for approximately 70% of the CF chromosomes identified in North Ameri can Caucasians. Over 400 identified mutations constitute the remainder . It is now possible to screen patients for the presence of many of th ese genetic mutations, thus establishing the diagnosis of CF or defini ng a carrier state. We report an unusual case of a 17-year-old male wi th chronic sinusitis, mild pulmonary disease, and pancreatic sufficien cy with nondiagnostic sweat chloride levels diagnosed to have CF after DNA analysis. This technique may thus serve as an important tool that pediatricians and otolaryngologists can use to diagnose children susp ected of having CF.