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Carrier of CF mutation

I am 34 years old at 21st gestational week. I am a carrier of r75Q after checking for 85% of CF mutations. My husband was checked for 99% of CF mutations and he was found to carry S977C (unknown clinical importance). The genetist expert advised us not to proceed to amniocentesis, since the mutation I carry, when combined with another typical CF mutation, in a worst-case scenario would lead to CF with only mild symptoms. I would like to ask if you agree with his opinion/assessment?
Dear friend,
You are 34 years old at 21st gestational week and you carry the R75Q mutation. Your husband carries the S977C mutation.
Up to date, there have been more than 2000 CF mutations discovered, but it is not possible to determine their clinical importance based on an amino acid replacepment in the CFTR protein, which may change the amount of protein produced, or the function of protein produced.
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 R75Q mutation has been detected in 75 chromosomes and causes atypical, monosymptomatic presentations of the disease (pancreatitis, bronchiectases, sterility) when combined with a typical CF mutation.
The S977C mutation is not described in the international literature, so its importance remains unknown.
The fetus has a 75% chance to carry one, or none, of the above mutations, so, in this case, it will be a healthy baby. There is a 25% chance to carry both mutations (R75Q/S97C), so in the worst-case scenario the baby would have a monosymptomatic CF, whereas in the best-case scenario it will not have CF.
The advanced stage of the pregnancy, the small chance for a mild, atypical monosymptomatic CF, in combination with the increase of life expectancy of the CF patients, as a result of the symptomatic treatment, and the expected further increase of the life expectancy due to the introduction of new, radical treatments, are the reasons that make me agree with the opinion of the genetist expert.

Yours friendly,
Stavros D. Doudounakis