Use of the ICM method in clinical practice in a patient with the c.2900T>C variant in trans with c.1521_1523delCTT of the CFTR gene

Cystic fibrosis (CF) is a disease caused by pathogenic variants in the CFTR gene. The greatest difficulty at the moment is assessing the contribution to the development of the disease of rare and previously unidentified genetic variants (mutations), mutations of uncertain clinical significance, as well as determining the genotype-phenotype relationship. Additional diagnostic methods are needed due to the large number of patients with borderline sweat test values. Purpose of the study: to study the pathogenicity of the c.2900T>C variant of the CFTR gene in a patient with the c.1521_1523delCTT and c.2900T>C variants in a heterozygous state based on an assessment of the functional activity of epithelial ion channels (ENaC, CFTR, CaCCs). Materials and methods: clinical information about the patient from the medical history, intestinal current measurement (ICM) method. Results: the patient had borderline sweat test results, normal pancreatic fecal elastase levels, spirometry within the age norm, which corresponds to a mild course of the disease. The ICM method showed normal chloride channel function. For the first time in Russia, clinical features of a patient with the genetic variant c.2900T>C in trans -position with the variant c.1521_1523delCTT are described. Conclusion: the results of the examination, the clinical course of the disease correspond to a mild course of the disease or its absence. Additional use of the ICM method confirmed the normal function of the CFTR channel in a patient carrying the c.2900T>C variant of the CFTR gene in trans-position with the c.1521_1523delCTT variant.