Leung GJ, et al. - Two thousand six hundred twelve patients were recruited in a study by the experts in order to advance the understanding of the natural history of cystic fibrosis (CF) by contrasting lung function and body mass index z-score (zBMI) among patients with different genotypes and recognize a genotype with outcomes most comparable to homozygous ΔF508 patients. On the basis of the genotype, patients were classified into one of five groups. Mainly adult patients who had non-mild forms of CF with a similar functional allele classification were recognized to have a lung function trajectory comparable to individuals with the homozygous ΔF508 genotype. No significant difference in the rates of zBMI change could be ascertained among the genotype groups during the study period. Hence, adjusted rates of reduced lung function and zBMI over ten years were rendered by this population-based study of Canadian CF patients. Further, to evaluate the long-term effectiveness of emerging CF therapies, there were different genotypes with comparable rates of lung function decline to individuals of the homozygous ΔF508 group that supported the use of multiple comparison groups.