How Does CF Develop and How Is It Inherited?
CF develops when a child inherits two non-functioning variants of the CFTR gene, one from the mother and one from the father. This is known as autosomal recessive inheritance.
If only one partner is a carrier, the risk of having a child with CF is very low.
If both partners are carriers, each pregnancy carries the following risk:
-25% chance of having a child with CF
-50% chance of having a child who is a carrier
-25% chance of having a child without the mutation
Why Does Testing Make Sense?
Couples planning a family: testing enables informed decision making and timely planning of the next steps.
Couples before IVF: the result is important for choosing the most suitable strategy.
Men with abnormal semen analysis results: some CFTR mutations are associated with congenital bilateral absence of the vas deferens, CBAVD, and subsequent azoospermia.
What Does the Test Detect?
Genetic testing analyses the CFTR gene. In practice, the most common pathogenic variants are usually detected, including the most frequent F508del mutation. A broader scope of testing can also be selected if appropriate.
Important: no test usually detects all possible CFTR variants. This means there is always a residual risk, which will be explained to you by a clinical geneticist.
What Does the Result Mean?
Negative result: significantly reduces the likelihood that you are a carrier, within the scope of the test performed.
Positive result, carrier: you are not ill, but it is advisable for your partner to be tested as well.
Both partners are carriers: we will offer genetic counselling and options for managing the risk, depending on the situation. These may include IVF with PGT-M, allowing the selection of embryos without CF, or prenatal diagnosis.
