CFTR test

Mutations in the CFTR gene contribute to the development of cystic fibrosis and some forms of infertility in men, such as obstructive azoospermia (obstruction of the seminal ducts) or congenital bilateral absence of vas deferens (CBAVD).

CFTR protein

The CFTR gene has its locus on the long arm of chromosome 7. It is responsible for the production of the CFTR protein, which is responsible for the correct formation of the membrane channel for chloride ions. 

Mutations in the CFTR gene in humans are the cause of the genetic disease cystic fibrosis. It is a disease characterised by abnormal functioning of the mucus glands in the respiratory, digestive and reproductive systems, among others. The increased volume and viscosity of the mucus blocks the correct functioning of the above-mentioned systems. Cystic fibrosis leads to complications such as infertility and diabetes. Treatment of cystic fibrosis is limited to relieving its symptoms only. Cystic fibrosis is inherited in an autosomal recessive manner, i.e. an individual must have two copies of the mutated CFTR gene in order to be affected.

What is autosomal recessive inheritance? Autosomal recessive inheritance means that a person must inherit two altered copies of the same gene (one altered copy from each parent) to develop the disease.  If a person inherits one altered copy and one normal copy, then in most cases, that person will be a healthy carrier because the presence of the normal copy balances the presence of the altered copy. Being a carrier means that you are not affected by the disease, but you carry an altered copy of one gene from the pair.

Mutation of the CFTR gene in men

Mutations within the CFTR gene can most commonly cause male azoospermia (no sperm in the ejaculate), severe oligozoospermia (low sperm count in the ejaculate), or congenital absence of the vas deferens or their bilateral aplasia (failure to form). 

The abnormal CFTR protein, which results from mutations in this gene, contributes to the abnormal development of the Wolff ducts (from the Wolff ducts, among other things, the vas deferens and seminal vesicles develop), leading to pathology in the epididymis, as well as the seminal vesicles.

CFTR gene mutation in women

Mutation of the CFTR gene in women can cause menstrual disorders (secondary amenorrhoea), as well as the secretion of excessively thick mucus in the cervix, resulting in impaired migration of sperm during their journey to the egg.

CFTR test result

In men, in the case of a CFTR gene mutation with bilateral absence of the vas deferens but without symptoms of cystic fibrosis, it is possible to perform a testicular biopsy and obtain sperm that can be used during in vitro fertilisation by ICSI or IMSI.

When to perform the CFTR test? CFTR gene mutation testing is recommended for men with known obstructive azoospermia, as it accounts for 7-51% cases of azoospermia. Decreased semen volume and semen pH are also symptoms that may indicate a CFTR gene mutation. CFTR gene mutation testing is also recommended to be performed for all patients, especially when one partner has been diagnosed with this mutation, in order to determine the risk of a genetic disease in the child.

How to prepare for CFTR gene mutation testing?

You do not need to be specially prepared for the CFTR genetic test. It is performed at Invimed facilities from the patient's venous whole blood. The CFTR result is ready for collection after 4-6 weeks.

What does the CFTR gene mutation test check?

The study identifies the most common CFTR gene defects occurring in male infertility. It takes into account mutations in the Caucasian population as well as mutations specific to the Polish population. During the analysis of the patient's genetic material, not only the most common CFTR gene defects can be detected, but also very rare mutations.

A total of 290 of these are analysed in Invimed clinics. 16 of these are mutations common in the Polish population, occurring in 77% mutant copies of the CFTR gene.

Where to perform the CFTR test?

The test for the CFTR gene mutation is performed at every Invimed clinic during collection centre opening hours. You do not need to be registered, just turn up at registration and then go to the collection centre.