Association between phenotypic and genotypic characteristics and disease severity in individuals with cystic fibrosis

Gabriella Vieira Carneiro, Fabiana Sodré de Oliveira, Leandro Alves Pereira, Érica Rodrigues Mariano de Almeida Rezende, Luciana Carneiro Pereira Gonçalves, Vivian Mara Gonçalves de Oliveira Azevedo

To analyze the association between phenotypic and genotypic characteristics and disease severity in individuals with cystic fibrosis treated at a reference center in Minas Gerais, Brazil. This is a retrospective study that collected clinical and laboratory data, respiratory and gastrointestinal manifestations, type of treatment, Shwachman-Kulczycki score, and mutations from the patients' medical records. The sample included 50 participants aged one to 33 years, 50% of whom were female. Out of the one hundred alleles of the Cystic Fibrosis Transmembrane Conductance Regulator gene, the most prevalent mutations were DeltaF508 (45%) and S4X (18%). Mutation groups were only associated with pancreatic insufficiency (p=0.013) and not with disease severity (p=0.073). The latter presented an association with colonization by Pseudomonas aeruginosa and Staphylococcus aureus (p=0.007) and with underweight (p=0.036). Death was associated with age at diagnosis (p=0.016), respiratory symptomatology (p=0.013), colonization (p=0.024), underweight (p=0.017), and hospitalization (p=0.003). We could identify the association of mutations with pancreatic insufficiency; the association of Staphylococcus aureus colonization and underweight with disease severity; and the lack of association between mutations and disease severity. Environmental factors should be investigated more thoroughly since they seem to have an important effect on disease severity.