So mutations in CF are classified by the severity of the impact on the production of the CFTR.
But an individual may have two different CFTR mutations.
I assume that the least severe mutation of the two is the most relevant to the phenotype. e.g It is more favourable to have a class I and class II mutation that to have 2 class I mutation.
However, I cannot find any references to support this or explain the molecular interaction between classes. Additionally, I fear that it may be more complex than this.
The purpose for knowing this is I want to control for CFTR class in regression analysis but I am removing individuals on ivacaftor or similar so I am talking about the effect purely at the baseline biological level rather than differential access to potentiator therapies.