Amniocentesis

Question

I was checked for >98% of CF mutations and I was found to carry the DF508 one. I am pregnant, therefor my husband was checked as well. If the results are negative, then the fetus has a 50% chance to be a carrier? If my husband is found to carry the same gene, then there is a 25% chance for the fetus to have CF and I must do an amniocentesis to check this possibility? If my husband has another mutation, then what must we do? Thank you.

Answer

Dear friend,
You are pregnant and you are checked for the largest possible number of CF mutations and you were found to be a carrier of the DF508 mutation.
You correctly state that you husband has to be checked as well (I trust for the largest possible number of CF mutations as well).
If his results are negative, then the fetus has a 50% chance to be a carrier (carriers are healthy) of the DF508 mutation, and a 50% chance to carry no mutation at all.
If your husband is found to be a carrier of the DF508 mutation like you, or of any other CF mutation, then the fetus has a 25% chance to suffer from CF (i.e. it will carry two CF mutations, one from each parent), a 50% chance to be a carrier of one CF mutation (either from the mother, or from the father), and a 25% chance to carry none. For this reason you must do an amniocentesis to check the fetus. In case it has CF, then you will have to decide, after you discuss the case with your doctor and a genetician, about the future of the pregnancy.
Yours friendly,
Dr. Stavros Doudounakis

14.08.2015