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Infertility
- Question
- I have 2 sons of 29 and 27 years. Both are not known with cystic fibrosis nor with recurrent respiratory infections. Now it happens that my eldest son has been shown to have a form of CF with infertility. We were quite surprised by this. Do you know this type of CF where a person does not have any complaint but is still suffering from CF?
- Answer
- Dear Ecorn-user,
Cystic fibrosis is caused by mutations (=alterations) in the CFTR gene. Every individual carries 2 CFTR genes; one inherited via his father, one inherited via his mother. If on both CFTR genes a severe mutation is present one suffers from cystic fibrosis. If a severe mutation is present on one of the CFTR genes but a mild mutation on the other gene, milder CF-like symptoms occur. If one only carries one CFTR mutation and no mutation on the second CFTR gene one is not ill, one is just carrying the CF mutation.
95% of male CF patients have infertility as part of the total CF disease expression: they also suffer from disease in the lungs, the pancreas and other organs. A small percentage of infertile men are infertile because they do not have a vas deferens. This form of infertility is know as congenintal absence of the vas deferens (CAVD). The majority of these CAVD men carry one severe CFTR mutation and one mild CFTR mutation. Mainly these subjects suffer just from infertility but do not have the problems in the lung or in the pancreas that patients with classic CF have. Only when sensitive tests are done will a mild form of lung disease be established in some of these CAVD patients. CAVD patients are thus best referred to a pulmonologist for further examination.
In the testicle, the sperm cells of CAVD patients are usually normal, so via in vitro fertilization parenting is possible. But couples where the man has CAVD carry a higher chance of having a child with cystic fibrosis. So it is important that also the partner be screened for carrying a CFTR mutation. Only if both parents carry a CFTR mutation is there a chance of 1 in 4 that their child will have CF.
So to come back to your original question, this form of CF with just male infertility is well known.
Yours sincerely,
Prof. K De Boeck - 26.01.2009
