Please note: While some information will still be current in a year, other information may already be out of date in three months time. If you are in any doubt, please feel free to ask.


I have been identified with dF508 as my first mutation, and Q493X. What does it mean? Im really confused with the numbers, the letters. I have no clue but i really would like to know as I have cf.

Thank you for your question. The numbers and letters are often confusing. The numbers and letters represent the genetic mutation. dF508 is the commonest mutation seen in CF and belongs to class II. Q493X is a much rarer mutation and is a class I. The combination of these mutations in the literature is likely to lead to a clinical picture similar to those who have two copies of the dF508 mutation (i.e. lung disease and pancreatic insufficiency), however, as with all genetics, the prognosis is difficult to predict based on the genotype alone.
It is not known what the prognosis for your combination of mutations is, but in our experience those with similar genetics can have very different symptoms.
Of note to you, Q493X is a particular mutation which can be helped by a new drug called Ataluren (PTC-124). This is currently in clinical trial stage and something to be aware of.
Best Wishes,

Dr Stephen Rowan
Respiratory Research Fellow

Prof Stuart Elborn
Consultant Physician Belfast
The answer is edited by: Prof Stuart Elborn