Study of human ribosomal gene complex in cystic fibrosis

Increasing the life expectancy of patients with CF is an urgent healthcare task all over the world. According to the Register of patients with cystic fibrosis in the Russian Federation (2020), the number of patients over 18 years of age is 26.5%. Assumably, cystic fibrosis can be used as a model of accelerated aging to study the aging process in general.Aim of the study was to analyze the number of rDNA copies in a sample of cystic fibrosis patients at different ages and with lethal outcome in relation to lung function, complications, and respiratory tract infections.Methods. We studied DNA samples isolated by the standard method from peripheral blood leukocytes of 277 patients diagnosed with cystic fibrosis. 998 DNA samples from healthy volunteers were used as a control group.Results. The study showed that the genomes of patients with CF contain more rDNA copies than those of control patients. The greatest number of copies of ribosomal genes was observed in DNA samples from deceased patients (p < 0.001) and was associated with more severe disease course. Among all CF patients, the largest number of rDNA copies in the genome was registered in patients with the lowest FEV1 values (less than 40%). It was found that patients with chronic Burkholderia cepacia complex infection had a significantly higher number of copies of ribosomal repeats than the total sample (p = 0.001) and the adults (p = 0.014). The number of ribosomal repeats did not differ between patients with other chronic respiratory tract infections.Conclusion. In the group of deceased patients, the patients with low respiratory function and Burkholderia cepacia complex infection had the highest number of rDNA copies in the genome, and the differences were significant. It can be assumed that the number of rDNA copies in the genome of CF patients is an additional prognostic marker that is associated with the patient’s life expectancy.