mutations are ranked in "class" from class 5 (i think, it might be 4) to class 1. class 1 is generally considered the worst because it means the ion transfer is completely inhibited. BUT this gets a little sketchy for a couple of reasons:
1) most people think that DF508 is the "most severe" mutation and that people with two of these genes (double deltas) have the "most severe" presentation of CF. in reality, DF508 is a class 2 mutation.
2) the LEAST SEVERE mutation control -- so if you have a class 4 and a class 2 (DF508 and a more "mild" mutation, for example), the official "prognosis" is that your CF will follow the course of the class 4 mutation and your symptoms will either be "mild" or "late onset." most "atypical" or "mild" or whatever CFers also have a DF508 gene, just because that is by far the most common.
3) finally, there is very little consensus even within the medical community about what mutations mean. my doc and i had a long convo once where i was told "look, we can sit here and hypothesis all we want. the simply fact is that MOST CFers with so-called "mild" mutations have fewer symptoms than people with more severe mutations. but knowing that doesn't do you much good when you're treating a patient who medically speaking SHOULD have "mild" CF because of their mutations but instead needs a lung transplant. and that does happen." i thought that was a great explanation. yes, medical science can maybe make some generalizations like "people with certain mutations often live longer" or whatever (and there is some truth to that), but in the end each patient is different and you need a doctor willing to look at the WHOLE picture, not just mutations and generalized, textbook predictions. most people only get chicken pox once, after all, but i got it twice -- and it was no less "real" the second time around.
