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Genotype in CF

My two grandsons (one 18 months, the other 4 years) have CF with genotype F508del (egzon 10) and S466X (egzon 10) in CFTR gen. Can you tell me to which class of mutation belongs S466X and what are the prognosis for the children with this genotype.
Thank you very much for your question. The S466X is a class I mutation, F508del is a class II mutation. The S566X mutation is most common amongst the Middle Eastern area such as Turkey, Greece, Iran and India (Sermet-Gaudelus et al, 2005). F508del is a common mutation. The prognosis for this combination of mutations is not known, however, is likely to follow a similar pattern to those who have 2 copies of F508del. This is usually associated with greater involvement of lung disease and pancreatic insufficiency. It is important to note, however, that making a prognosis based only on genotype is very difficult. People with the same two copies of the mutated CFTR gene may experience very different symptoms.

Sermet-Gaudelus et al, 2005. Chloride Transport in Nasal Ciliated Cells of Cystic Fibrosis Heterozygotes. American Journal of Respiratory and Critical Care Medicine;171:1026-1031.

Best wishes
Lisa Kent, Lauren Green,
Stuart Elborn
The answer is edited by: Prof Stuart Elborn