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Desire to have children
- Question
- Dear expert team,
My husband and I have an unfulfilled desire to have children. My husband was diagnosed with oligozoospermia. Subsequently, a heterozygous mutation R553X of the CFTR gene was found. Unfortunately, I was then also diagnosed with a mutation in the CFTR gene, namely R117H-T7. In case of a compound heterozygosity in a future child of ours - what would be the consequences? According to our human genetic counselling, a mild form of CF would be possible. What does that mean and how certain one can be?
Many thanks. - Answer
- Dear questioner,
A severe mutation (R553X, Stopcodon) was detected in your husband's CFTR gene und a mild mutation (R117H with T7) in yours. Under the condition that the second allel is normal in both of you, 25 % of your children with have the allels R117H and R553X and will thus belong to the so called compound heterozygous individuals (risk: 25% corresponds to 1 in 4). Probably, most of the children will be healthy what cystic fibrosis is concerned despite the compound-heterozygosity; there is a low risk for mild symptoms of the disease, in boys CBAVD (Congenital Bilateral Aplasia of the Vas Deferens = bilateral anomaly of the spermatic cords) can occur and very rarely patients with this genotype can also have a severe course of the disease.
I have not found exact figures about this topic. According to my opinion, a quite recent French study is comparable. In this study (Thauvin-Robinet et al., J Med Genet 2009, 46, 752-758), genetic carriers respectively patients with the severe mutation ∆ F508 and the mutation R117H were listed in the context of a CF network.
Out of the expected 3650 compound heterozygous individuals with ∆ F508 and the mutation R117H-7T, 112 individuals (3.1%) showed CF-related symptoms - in the majority of the cases the symptoms were mild but in occasional cases the individuals also showed the complete picture of CF. Potentially, a number of unrecorded cases has to be assumed for this study; the risk however, still remains small.
Yours sincerely,
Prof. Dr. Rainer König - 04.03.2013
