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how serious

my daughter has g551d and 3659del severe is this?
Dear questionner
Thank you for your question to ECORN-CF.

Firstly, considered separately, the G551D mutation is known as a missense mutation that affects the function of CFTR channels at the cell surface (1).
This 3659delC mutation is known as an insertion/deletion mutation. This type of mutation is expected to significantly disrupt CFTR protein production and result in little or no functional CFTR protein in the cell (2). Both mutations are known CF causing mutations.

CFTR2 (a database of the functional and clinical characteristics of CF patients according to genotype) (2) summarises 1068 individuals with CF with the G551D mutation and another mutation (including the 3659delC mutation). These patients had mild to moderate lung function impairment, the majority (96%) were pancreatic insufficient and 57% had Pseudomonas aeruginosa lung infection.

It is important to keep in mind that there is a high variability in phenotype (i.e. how a person’s presents) within identical CFTR genotypes (3). As definite modifier genes remain to be identified we support consensus statements advising that clinicians should not use genotype alone to predict clinical outcomes at the time of diagnosis (4).
The individual clinical course and especially the degree of lung involvement cannot be predicted according to the genotype alone. Therefore, it is very important that the individual patient is seen regularly in a certified CF center and follows his individual treatment program.

I hope you have found this information helpful.

Best Wishes
Katherine O'Neill


1. Kerem B, Rommens JM, Buchanan JA, et al. Identification of the cystic fibrosis gene: genetic analysis. Science 1989;245:1073-1080

3.Loubieres, Y., et al., Association between genetically determined pancreatic status and lung disease in adult cystic fibrosis patients. Chest, 2002. 121(1): p. 73-80.
4.Castellani, C., et al., Consensus on the use and interpretation of cystic fibrosis mutation analysis in clinical practice. J Cyst Fibros, 2008. 7(3): p. 179-96.
The answer is edited by: Katherine O'Neill