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Nucleoitc change of unknown significance

Question
I am 16 weeks pregnant and I was tested for 99% of CF mutations for purely preventive reasons, as there is no history of CF in my family, or in my husband’s family. The results showed the nucleotic change c.1001G>A (.Arg334Gin) in the CFTR gene in heterozygote condition and that there are not enough data from the literature concerning its pathogenic significance. What does this mean exactly? Am I a carrier of the CF gene? The recommendation was for my husband to get tested for the 99% of CF mutations. The results will come out in a month? What are the possible scenarios, if he is found to carry a mutation? Thank you!
Answer
Dear friend,
You are 16 weeks pregnant and you were tested for 99% of the CF mutations. The results showed the nucleotic change c.1001G>A (.Arg.334Gin), i.e. the R334Q CF mutation.
In the CFTR2 database, which is the biggest reference system created by information about the clinical importance of each mutation collected from national registries, or from large CF centers, for 89502 patients, the importance of just 374 mutations has been established.
312 of these mutations cause CF
36 present various clinical symptoms
13 mutations do not cause mutations
13 mutations are of unknown importance
The mutation R334Q has been described in eight chromosomes and belongs to the varying clinical consequence group of CF mutations. Therefore, you are a carrier of a CF gene of varying clinical expression. This is the reason that it was recommended for your husband to get tested for 99% of the CF mutations.
If your husband is found to carry a CF mutation, the following scenarios apply: There is a 25% chance for the fetus to carry none of the two mutations, so it will be healthy. There is a 50% chance to carry one of the two mutations, so it will be a carrier of a CF gene, just like you. It will be healthy. Lastly, there is a 25% for the fetus to carry both mutations, in which case it will suffer from CF.
Yours friendly,
Dr. Stavros Doudounakis
09.02.2018