Chance of Cystic Fibrosis

Întrebare

Our son is 16 months old and has not shown any symptoms of cystic fibrosis. However, during prenatal genetic testing, we found that he had inherited two CFTR variants: c.358G>A (p.Ala120Thr) from me and 5T/TG11 from his father.

Given these findings, is there a significant risk that our son could develop respiratory problems, male infertility, or any other health issues related to CFTR later in life?

Thank you very much for your time.

Raspuns

Based on the information you have provided, the overall picture is very reassuring.

The **5T/TG11** variant is currently considered **non-CF-causing** according to the available scientific evidence. Although, in rare cases, it may be associated with mild **CFTR-related disorders (CFTR-RD)**, it is not expected to cause classic cystic fibrosis, even when found in combination with a CF-causing variant.

In your child's case, the second variant, **c.358G>A (p.Ala120Thr)**, has been classified as a **Variant of Uncertain Significance (VUS)**. This means that there is currently insufficient scientific evidence to determine whether it is disease-causing. According to international guidelines, a VUS should not be considered a pathogenic variant unless additional evidence becomes available.

Furthermore, the fact that your son is already 16 months old, is developing normally, and has not shown symptoms such as chronic cough, recurrent respiratory infections, poor weight gain, or pancreatic insufficiency is another highly reassuring finding.

Based on the currently available evidence, the likelihood that he will develop classic cystic fibrosis appears to be extremely low. It is not possible to completely exclude the possibility of a mild CFTR-related manifestation later in life, such as congenital bilateral absence of the vas deferens (CBAVD), which may lead to male infertility, or, much more rarely, mild manifestations affecting other organ systems. However, even these outcomes are considered less likely when one variant is a VUS and the other is the relatively benign **5T/TG11** allele.

Overall, based on current scientific knowledge, there is no evidence that this specific genotype predisposes an individual to developing classic cystic fibrosis. Continued routine pediatric follow-up and, if recommended by the treating physician or a clinical geneticist, a sweat chloride test may provide additional reassurance regarding normal CFTR function.
Best regards,
M. Poulou

06.07.2026