Symptoms that affect the reproductive system are common in people with cystic fibrosis (CF), a disease caused by genetic mutations that lead to impairment of the cystic fibrosis transmembrane regulator (CFTR) protein.
Across sexes, people with CF tend to undergo puberty and sexual development at a later age than their peers. Other reproductive symptoms depend on a patient’s individual anatomy, but many males can experience infertility, and females may have irregular menstrual cycles and difficulty becoming pregnant.
Both men and women with the disease can pass it on to their biological children.
Notably, however, while fertility may be affected by CF, most people with the disorder experience no problems with sexual drive or function related to their disease.
The CFTR protein that is impaired in cystic fibrosis is critical for the function of secretory cells in the body that produce mucus. Normally, this protein is present on the cell’s surface, where it acts like a gate, helping to regulate the flow of ions and water in and out of cells. The proper movement of ions and water, in turn, allows cells to make a thin, watery mucus.
Mucus — normally a slippery or sometimes runny substance — is produced by many bodily tissues and is critical for health. As a prime example, mucus in the lungs works to trap airborne irritants and disease-causing microorganisms, thereby protecting the body against disease. It’s also important for the proper function of the intestines, and plays a critical role in the reproductive system.
In CF, the dysfunction of the CFTR protein results in a disruption in the movement of ions and water, which leads to the production of mucus that is abnormally thick and sticky. Thick mucus can clog up tissues, ducts, and organs, leading to a range of problems and a host of symptoms.
Most people with CF experience respiratory system problems such as persistent coughing, increased susceptibility to lung infections, bronchitis, wheezing, and shortness of breath. Digestive system problems also are common and include diarrhea, severe constipation, malnutrition, or foul-smelling and greasy stools.
Reproductive system problems also occur, though men and women face different issues.
CF and the male reproductive system
Like the sex drive, sperm production is normal in most males with CF. However, the thick mucus produced by CF can impair the reproductive process.
The vas deferens, in men, is a duct that transports sperm from the epididymis — a duct behind the testes — where it is stored prior to ejaculation. In CF, this duct can get blocked with mucus, obstructing the passage of sperm. Such a blockage can lead to infertility.
Males with CF also are commonly affected by a condition called congenital bilateral absence of the vas deferens, in which the vas deferens is completely absent.
In such cases, men who wish to have biological children may opt for assisted reproductive technologies. Such options include surgical sperm retrieval or testicular sperm aspiration (also known as MESA or TESA), followed by in-vitro fertilization.
Men with CF wanting to biologically reproduce should consult their urologist to identify the best options for them.
CF and the female reproductive system
While reproductive system symptoms are much less common in women with CF in comparison with men with the disease, female patients also can experience a range of problems. Women with CF may have irregular or delayed menstrual periods, or have periods that are absent or stop unexpectedly.
The thickening of cervical mucus can affect the movement of sperm across the cervix, making it difficult for sperm cells to reach the egg and start a pregnancy. Inflammation of the cervix also may occur in CF.
In addition to the direct effects of thick mucus on the reproductive tract, female CF patients may see their fertility indirectly impacted by other disease symptoms. For example, digestive problems caused by CF can lead to inadequate nutrition, which can, in turn, cause irregular ovulation, affecting the release of eggs from the ovaries.
Although CF can bring about reproductive challenges for some female patients, most are able to become pregnant. When they cannot, there are other options, such as assisted reproductive technologies, that can help women with cystic fibrosis to have biological children. Ensuring proper nutrition before and during pregnancy is key for the health of both mother and baby.
The risk of passing CF to future generations
CF is inherited in an autosomal recessive manner. That means that a person must have two mutated copies of the CFTR gene that codes for the CFTR protein to develop the disease.
People inherit two copies of the CFTR gene, one from each biological parent. People who have one mutated copy of the CFTR, and one normal, or non-mutated copy will not develop the disease. However, such individuals are referred to as “carriers” of CF, because they can pass the disease-causing gene to their biological children.
If two people who both are carriers have a biological child, there is a 25% chance that the child will inherit both mutated gene copies and have CF. There also is a 50% chance that the child, like his or her parents, would have just one mutated copy and be a carrier. Finally, there is a 25% chance that a baby born to two carrier parents would not inherit any mutated copies of the CFTR gene and would neither have the disease nor be a carrier.
If a person who has CF decides to have a biological child, there is a 100% chance that the parent would pass along a mutated copy of the CFTR gene to the child. The child would either have CF or be a carrier, depending on whether or not he or she inherited a second mutated copy of the gene from the other biological parent.
To assist people with CF who wish to have a biological child, prenatal genetic testing and genetic counseling are offered at many reproductive and gynecology clinics. People who suspect or know about their CF status should seek these services when they plan to have biological children.
For those who are not aware of their CF disease status, prenatal genetic testing for CF is offered routinely as an “opt-in” or “opt-out” choice at most clinics. The decision to have the testing is left to each individual.
Last updated: Aug. 11, 2021
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