Cystic fibrosis and fertility

A genetic cause of obstructive azoospermia. Patients who are cystic fibrosis carriers can have fertility issues

What is cystic fibrosis?

Cystic fibrosis is a chronic and progressive hereditary disorder that becomes apparent during early infancy and that affects multiple body organs such as the lungs, intestines, pancreas, liver and so on. It is caused by thick mucus production that leads to obstructions and infections.

Cystic fibrosis is one of the most common genetic disorders amongst the Caucasian race and approximately one in every 20 to 25 people is a healthy carrier.

What is it for? What is its purpose?

Male patients who have cystic fibrosis can have fertility issues. A large number of these males have azoospermia. In other words, they do not have spermatozoa in their semen because they do not have ducts called vas deferens through which spermatozoa travel before they are ejected in the ejaculate. These spermatozoa can be retrieved by means of testicular puncture so that they can be used to fertilise the female partner’s ova using the ICSI technique that consists of spermatozoa microinjection.

What does a cystic fibrosis genetic analysis consist of?

A cystic fibrosis genetic analysis includes an analysis of the most common mutations in the CTFR gene. They represent 80% of all cases.

Cystic fibrosis is a recessive hereditary disorder. We all have two copies of the gene, one from each of our parents. If a person has only one copy of the mutated gene, then he or she is a carrier but is not affected by the disorder. Both copies of the gene need to be mutated for a person to have the disorder.

When is it advisable?

From a fertility point of view, this test is advisable for males with azoospermia (an absence of spermatozoa in the ejaculate) or males with severe criptozoospermia.

If a patient has a family history of the disorder or symptoms that would appear to suggest its presence, a genetic analysis is advisable in order to rule out that a person is a cystic fibrosis carrier.

The genetic analysis can also be performed on foetuses by means of amniocentesis or a chorionic biopsy.

When cystic fibrosis sufferers decide to have children they need to be given genetics guidance by their doctor or geneticist. The specialist will advise extending the analysis to include the partner and, should the result be positive, the couple will be given two options: either prenatal diagnosis or pre-implantation diagnosis.

Pre-implantation genetic diagnosis (PGD) is an assisted reproduction technique that facilitates selection of healthy embryos in terms of cystic fibrosis. That is, embryos that can be transferred to the mother's uterus so that the couple can have healthy children that are free from the disease.