Nasal Potential Difference in Cystic Fibrosis considering SevereCFTRMutations

Abstract

The gold standard for diagnosing cystic fibrosis (CF) is a sweat chloride value above 60 mEq/L. However, this historical and important tool has limitations; other techniques should be studied, including the nasal potential difference (NPD) test.CFTRgene sequencing can identifyCFTRmutations, but this method is time-consuming and too expensive to be used in all CF centers. The present study compared CF patients with two classes I-IIICFTRmutations (10 patients) (G1), CF patients with classes IV-VICFTRmutations (five patients) (G2), and 21 healthy subjects (G3). The CF patients and healthy subjects also underwent the NPD test. A statistical analysis was performed using the Mann-Whitney, Kruskal-Wallis,χ2, and Fisher’s exact tests,α=0.05. No differences were observed between the CF patients and healthy controls for the PDMax, Δamiloride, and Δchloride + free + amiloride markers from the NPD test. For the finger value, a difference between G2 and G3 was described. The Wilschanski index values were different between G1 and G3. In conclusion, our data showed that NPD is useful for CF diagnosis when classes I-IIICFTRmutations are screened. However, if classes IV-VI are considered, the NPD test showed an overlap in values with healthy subjects.