Complex alleles (CAs) arise when two or more nucleotide variants are present on a single allele. CAs of the CFTR gene complicate the cystic fibrosis diagnosis process, classification of pathogenic variants, and determination of the clinical picture of the disease and increase the need for additional studies to determine their pathogenicity and modulatory effect in response to targeted therapy. For several different populations around the world, characteristic CAs of the CFTR gene have been discovered, although in general the prevalence and pathogenicity of CAs have not been sufficiently studied. This review presents examples of using intestinal organoid models for assessments of the two most common and two rare CFTR CAs in individuals with cystic fibrosis in Russia.
Keywords: CFTR; CFTR modulators; complex allele; cystic fibrosis; intestinal organoid; targeted therapy.