Cystic fibrosis is a progressive, genetic disease, causing lung infections and the persistent loss of lung functions. Most men with cystic fibrosis are infertile due to the absence of the sperm canal (also known as CAVD). As a result, those with cystic fibrosis may turn to assisted reproductive technology (ART) to have genetic children.

What is cystic fibrosis?

Cystic fibrosis is a progressive genetic disorder affecting both males and females, which leads to persistent lung infections and reduces the patient’s ability to breathe. Beyond causing a loss of lung function over time, cystic fibrosis can also trigger damage to the digestive system and other organs in the body.

People with cystic fibrosis have a mutation in the CFTR gene (cystic fibrosis transmembrane conductance regulator). This mutation causes the CFTR protein to become dysfunctional and is then unable to move chloride within the lungs. Consequently, mucus clogs the airways in the lungs and traps bacteria, leading to infections, inflammation, and respiratory failure.

Cystic fibrosis and male fertility

Cystic fibrosis can have a significant impact on male fertility. The CFTR mutation can also cause congenital absence of the vas deferens (CAVD), the tube that brings sperm from the testicles to the penis. As a result, it is impossible for sperm to reach the urethra, be ejaculated, and fertilize the egg, leading to azoospermia (zero sperm count) and infertility. According to the Cystic Fibrosis Foundation, 97–98% of males with cystic fibrosis are infertile, but can use ART procedures to have biological children.

While clinical cystic fibrosis is only seen in those born from parents who both carried the CFTR mutation. However, those who inherit just one affected gene — known as CF carriers — are also at higher risk for infertility, despite not experiencing most symptoms of cystic fibrosis. 

Symptoms of cystic fibrosis

Typically, cystic fibrosis is detected by the age of two. Common symptoms of cystic fibrosis include persistent coughing, frequent lung infections, shortness of breath, male infertility, and poor growth or weight gain. As cystic fibrosis is a genetic disease, diagnosing this condition often requires multiple tests, including newborn screening, a sweat test, and a genetic or carrier test.

Treatment for cystic fibrosis

There are different methods of treatment that exist for cystic fibrosis, depending on the severity. Treating this disorder typically involves a combination of therapies, including airway clearance, inhaled medicines to thin the mucus, pancreatic enzyme supplements, and CFTR modulators to target the dysfunctional CFTR protein.

Treatments for male-factor infertility associated with cystic fibrosis mirror the treatments for other CAVD patients: a procedure to retrieve sperm directly from the testes (TESE/TESA), paired with  intracytoplasmic sperm injection (ICSI) and in vitro fertilization (IVF). Some with cystic fibrosis or who carry the CF gene may choose to use IVF with preimplantation genetic diagnosis — genetic screening for embryos — to prevent passing the CF gene to their children.