Male with cbavd, woman no abnormalities on the CFTR gene. What are the consequences?

Question

Because we wanted to start a family, but no children came, we went to a fertility centre. Tests revealed that there was no sperm in the ejaculate. Further tests revealed absence of the vas deferens and small seminal vesicles. Genetic tests revealed an abnormality in the CFTR gene. I am 33 years old, I have never had any symptoms of CF. I assume it will remain like that.

Since I have this genetic defect, tests were done in my partner. She does not have any CFTR gene defect, so we will have a fertility treatment ICSI. What are the risks to the baby? Will he be a carrier and that’s it?

Answer

Dear,

You state that you assume that you will never get symptoms from cystic fibrosis. Indeed if the diagnosis is CBAVD (congenital bilateral absence of the vas deferens) with a CF genotype, we know that most of the people do not develop lung problems during their lifetime. Since you do not list your mutations, we cannot be certain about it, you should discuss that with your doctor.

If your partner had carrier screening, that means she does not carry one of the 30 most frequent mutations in the Belgian population. This makes CF very unlikely but not impossible. It decreases the risk to 1/300. Only complete sequencing of the CFTR gene will bring certainty that someone does not carry CFTR mutation.

Most subjects with CBAVD have 1 severe mutation that can result in CF and 1 mild mutation that does not result in CF.

Under the assumption that your partner is not a carrier, there is a ½ chance that your child will inherit the severe mutation and thus be a CF carrier which will not have any consequences for his/her future health. If your child inherits the mild mutation, we would not even consider him/her a CF carrier and this will certainly not have any health problems for his/her future career.
We hope this brings some clarity for you.

Greetings
Prof. Kris De Boeck

08.05.2012