Mutations of the CFTR gene contribute to the development of cystic fibrosis and certain forms of infertility in men, such as obstructive azoospermia (obstruction of the sperm release pathway), obstruction of the vasa deferentia their bilateral absence.
The CFTR gene has its locus on the long arm of chromosome 7. It is responsible for the production of the CFTR protein, which in turn is responsible for the correct formation of the membrane channel for chloride ions. Mutations of the CFTR gene in humans are the cause of cystic fibrosis, which is a genetic disorder. This disease is manifested by abnormal functioning of mucous glands, e.g. in the respiratory, digestive and reproductive systems. Increased amount and viscosity of the mucus blocks the proper functioning of the above mentioned systems. Cystic fibrosis leads to complications, such as infertility and diabetes. The treatment of cystic fibrosis is limited to alleviating its symptoms. Cystic fibrosis is inherited in an autosomal recessive manner, i.e. an individual must have two copies of the damaged CFTR gene in order to become ill.
Autosomal recessive inheritance means that a person must inherit two abnormal copies of the same gene (one copy from each parent) in order for him/her to develop a disease. If a person inherits one abnormal gene copy of and one normal gene copy then, in most cases, the person will be a healthy carrier because the presence of the normal gene copy offsets the presence of the abnormal gene copy.
Being a carrier means you're not affected, but you carry an abnormal gene copy of one gene from a couple. Examples of autosomal recessive diseases are cystic fibrosis and sickle cell anaemia.
CFTR gene mutation in men
Mutations within the CFTR gene can most often cause azoospermia (lack of sperm cells in the ejaculate), severe oligozoospermia (low sperm count in the ejaculate), or congenital lack of vasa deferentia or their mutual aplasia (lack of formation) in men. Abnormal CFTR protein, resulting from the mutation of this gene, also contributes to the abnormal development of Wolff's ducts (from Wolff's ducts develop e.g. semen and seminal vesicles), which affects the process of sperm maturation, epididymides pathology, as well as seminal vesicles.
CFTR gene mutation in women
Mutation of the CFTR gene in women may cause menstrual disorders (secondary amenorrhea), as well as the secretion of too dense mucus in the cervix, which results in the difficult migration of sperm on their way to the egg cell.
CFTR test results:
In men, in case of a CFTR gene mutation in the bilateral absence of vasa deferentia, but without symptoms of cystic fibrosis, it is possible to perform a testicular biopsy and obtain sperm cells that can be used for in vitro fertilization using the ICSI method, or secured for the future (semen cryopreservation).
Testing of the CFTR gene is recommended in men with diagnosed azoospermia, as more than 3% of the causes of azoospermia are due to a mutation of the CFTR gene. A special indication for the CFTR test is the reduced volume of semen and its pH. This test is also recommended for all patients, especially if one of the partners has a CFTR gene mutation, to determine the risk of this disease in the child.
How to prepare for a CFTR test?
You don't need to be specially prepared for CFTR genetic test. It is performed at InviMed facilities from the patient's whole venous blood. The CFTR result can be collected after 4-6 weeks.
What does a CFR gene test look like?
The test also allows the identification of the most common CFTR gene defects occurring in male infertility. It takes into account mutations both in the white race population as well as mutations characteristic for the Polish population. During the analysis of the patient's genetic material it is possible to detect not only the most frequent defects of the CFTR gene, but also very rare mutations - 290 of them are analysed in InviMed clinics. 16 of them are frequent mutations in the Polish population, occurring in 77% of mutated copies of the CFTR gene.
Where to perform a CFTR test?
An test confirming CFTR gene mutation is performed at each InviMed clinic during the working hours of the collection point. You don't have to be registered, just come to the check-in and then go to the collection point.