What is the most common variant of cystic fibrosis?

The most common variant of cystic fibrosis is the F508del mutation. This mutation involves the deletion of phenylalanine at position 508 in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. It is the most prevalent mutation associated with cystic fibrosis, responsible for approximately 70% of CF alleles worldwide. The F508del variant leads to misfolding of the CFTR protein, which is crucial for the regulation of salt and water transport across cell membranes. This misfolding results in the protein being targeted for degradation rather than being correctly transported to the cell surface where it is needed, leading to the characteristic symptoms of cystic fibrosis.

Other variants listed, such as R117H and I1307K, are less commonly associated with cystic fibrosis compared to F508del. The term "DeltaF508" refers to the same mutation as F508del, as "Delta" denotes a deletion. Nonetheless, F508del is the name more typically used in clinical and genetic contexts. Understanding the prevalence and impact of the F508del mutation is crucial for genetic counseling, screening, and treatment strategies for cystic fibrosis patients.