BACKGROUND: The cystic fibrosis transmembrane conductance regulator (CFTR) gene 
mutation identification is being used with increased frequency to aid in the 
diagnosis of cystic fibrosis (CF) in those suspected with CF. Aim of this study 
was to identify diagnostic outcomes when CFTR mutational analysis was used in CF 
diagnosis. CFTR mutational analysis results were also compared with sweat 
chloride results.
METHODS: This study was done on all patients at our institution who had CFTR 
mutation analysis over a sevenyear period since August 2006.
RESULTS: A total of 315 patients underwent CFTR mutational analysis. Fifty-one 
(16.2%) patients had two mutations identified. Among them 32 had positive sweat 
chloride levels (≥60 mmol/L), while seven had borderline sweat chloride levels 
(40-59 mmol/L). An additional 70 patients (22.3%) had only one mutation 
identified. Among them eight had positive sweat chloride levels, and 17 had 
borderline sweat chloride levels. Fifty-five patients (17.5%) without CFTR 
mutations had either borderline (n=45) or positive (n=10) sweat chloride 
results. Three patients with a CF phenotype had negative CFTR analysis but 
elevated sweat chloride levels. In eighty-three patients (26.4%) CFTR mutational 
analysis was done without corresponding sweat chloride testing.
CONCLUSIONS: Although CFTR mutation analysis has improved the diagnostic 
capability for CF, its use either as the first step or the only test to diagnose 
CFTR dysfunction should be discouraged and CF diagnostic guidelines need to be 
followed.