Mutations R1162X/R1048G Wish to have another child

Question

My husband and I have a four-year-old daughter who inherited our mutations and suffers from a mild form of cystic fibrosis. She has lung infections quite often and the experts cannot give us any information about the course of the disease.

My husband and I would like to have a second child. The probability that both genes are inherited is 25%. We were told that our potential offspring might have a severe form of cystic fibrosis. Is that true?

Isn’t it the case that our daughter already inherited both genes [remark of translator: and although she inherited both genes, she only has a mild form], so actually a heavier form is not possible?

I thank you sincerely, I think this platform is very helpful.

Answer

Dear questioner,

Even if another child will have the same genotype (R1162X/R1048G) as the affected daughter, it is not predictable whether the course of the disease will be as mild as apparently in the case of your four-year-old daughter. The course of the disease does not only depend on the CFTR genotype, but also on other genetic and non-genetic factors. This is the reason why siblings with CF sometimes do have very different courses of the disease although they inherited the same mutations from their parents.

Even if the present genotype of the four-year-old daughter fits well with a rather mild course of the CF, it can not be guaranteed that the disease in another child is not more severe.

Yours sincerely,
Prof. Stuhrmann-Spangenberg

26.05.2009