Question

cystic fibrosis severity varies between similar patients with the δf508 allele mutation. what causes the difference in disease? recombination produces additional copies of the δf508 allele mutation. mutations in the modifier genes on the same chromosome affect the immune system. mutations in the modifier genes on other chromosomes affect the immune system. a lifestyle that includes running and saltwater inhalation treatments causes the difference.

Explanation:

Modifier genes can influence the severity of a disease phenotype. In cystic fibrosis with the ΔF508 allele mutation, mutations in modifier genes on non - homologous chromosomes (other chromosomes) can impact the immune system and thus the disease severity. Recombination does not produce additional copies of the ΔF508 allele in a way that explains severity differences as described. Modifier genes are not typically on the same chromosome in this context for explaining such differences. Lifestyle factors like running and saltwater inhalation treatments are not the main cause of the difference in disease severity compared to genetic modifier gene effects.

Answer:

C. Mutations in the modifier genes on other chromosomes affect the immune system.