Mutation 3199del6

Question

Hello
My 6 year old son has CF with mutations F508/3199del6. I try to find on the net the classification of mutation 3199del6 but I cannot find any information about it.
I inform you that my son was not born in France, no neonatal screening was done where we live.
According to your explanation, despite the fact that one person carries the F508 mutation which appears to be among the most severe, the association with a "lighter" mutation can alleviate the form of cystic fibrosis and have a properly functioning CFTR protein?
Thanks and Happy Holidays

Answer

Hello
I do not find a mutation 3199del6 in the international database CFTR2 of Johns Hopkins Hospital which gathers the information of nearly 100,000 patients with cystic fibrosis in the world.

I am sorry but I am not able to give you more precision on the nature of this "variant". Is it a simple variant, ie a modification of the gene without consequences on the functioning of the protein that it codes for synthesis or is it a mutation causing a dysfunction of the protein and in this case what is the class of this mutation, ie what is the type of dysfunction of the CFTR protein that it causes: I can not give you an answer.
Class I, II or III mutations are referred to as "severe" because they cause a greater dysfunction than Class IV, V or VI mutations. The mutated proteins encoded by these Class IV, V or VI mutations allow some chloride channel residual function. These mutations are called "mild" because, due to their residual functioning, the symptoms and the evolution of the disease in the patients are attenuated even if the other mutation of the patient is of class I, II or III .

The mutation F508del belongs to class II. The class of mutation 3199del is not currently known.

I remind you, however, that knowledge of mutations in a given individual does not predict the course of disease that depends on many other factors, both environmental and genetic (other than mutations in the CFTR gene). The relations that can be established between the mutations of the patients (the genotype) and the signs and the evolution of the disease (the phenotype) have only statistical value. They are found only when the data of a very large number of patients are analyzed.

Best regards
Gilles RAULT, CRCM of Roscoff

24.02.2017