Cystic Fibrosis

Background

Cystic fibrosis (CF) is an inherited genetic condition that mainly affects the lungs. However, people with CF can also have issues that affect their digestive system, reproductive system, and other organs in the body. Mucus glands typically produces mucus to cover and protect many different organs, including the lungs. The mucus glands in people who have CF are not able to properly regulate themselves. The mucus glands in individuals with cystic fibrosis produce more mucus than they should, and it is abnormally thick and sticky. This thick and sticky mucus leads to breathing problems and bacterial infections in the lungs, which can lead to permanent lung damage. Because the digestive system also requires mucus, some individuals with CF will also have thick and sticky mucus that will buildup in the pancreas, causing digestive problems. Most individuals who have CF are found through routine newborn screening.

There are forms of CF (called non-classic) that are not associated with potentially severe health concerns that people with classical CF have. In men, mucus lines their vas deferens, which are the tubes that carry sperm from the testicles out of the body. Some men with non-classic CF can have a condition called congenital absence of the vas deferens (CBAVD), which is when the vas deferens are blocked by mucus and do not develop properly. Men with CBAVD are infertile without undergoing fertility treatments, but they often will not develop the lung or gastrointestinal symptoms that people with classic CF have.

Genetics and inheritance

Both classic and non-classic CF are caused by mutations (changes) in the CFTR gene. The CFTR gene contains instructions to help regulate the amount of water moving in and out of tissues. Having this necessary balance helps create the normally thin, runny mucus that our body needs to function properly. Mutations in the CFTR gene lead to the body not being able to regulate this process properly, causing people with CF to produce thick, sticky mucus instead.

CF is inherited in an autosomal recessive pattern. This means an individual who has CF has inherited two non-working copies of the CFTR gene; the one they inherited from their mom is not working AND the one they inherited from their dad is not working. In the case of autosomal recessive conditions, if you inherit one working CFTR gene from a parent and one non-working CFTR gene from a parent, you are called a ‘carrier’ for CF. Carriers do not have CF, and typically do not have signs or features of CF.

Associated Health Issues

People with classic CF have persistent and long-lasting lung problems, such as constant coughing and wheezing, producing thick and sticky mucus or saliva, and chronic or recurring lung infections, such as pneumonia. Some individuals have digestive problems that lead to diarrhea, malnutrition, poor growth, and weight loss. For some individuals, this may even lead to diabetes because of poor insulin production (insulin is made in the pancreas).  Finally, some men may present with infertility only (CBAVD, discussed above), leading to the need for fertility treatments to father their own children.

Prognosis/possible treatments

Management of CF is a lifelong process that includes taking steps to prevent lung problems and improve weight gain. The majority of individuals with CF will require medications that will make their mucus thinner and easier to cough up, other medications to open the airway to make breathing easier, and antibiotics for frequent lung infections. In addition, some individuals affected will need Airway Clearance Therapies (ACT), which help them clear sticky, thick mucus through coughing. Those individuals with digestive system problems may require pancreatic enzymes to help digest food properly. Individuals with malnutrition may also need a high-calorie diet and vitamin supplements for healthy growth and development. With advances in treatment and appropriate management, individuals with classic cystic fibrosis typically live into their late thirties, or longer. Individuals with CBAVD may conceive children through assisted reproductive technologies.

 

Additional Resources:

Cystic Fibrosis Foundation

GeneReviews

Genetics Home Reference

Newborn Screening and CF


Last updated on Aug 9th, 2018