CFTR and cystic fibrosis: The reason why CF with isolate 203649 did not identify the 2A QTL in the BMWpop even though an SNB leaf blotch QTL was detected at this locus is not clear, and could be due to various reasons such as interactions between the CF effector complement and the genetic background of the BMWpop, or differences in the expression of effectors within different batches of CF.