Cystic Fibrosis

Cystic fibrosis (CF) is a genetic (inherited) chronic disease that can affect many parts of a child's body, including breathing, digestion, and growth. More than 30,000 people in the United States today are living with this disorder, according to the Cystic Fibrosis Foundation.

The disease causes a mutation (change) in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, a part of the body that determines your traits. This change allows chloride to get stuck inside the cells, leading to a build-up of thick, sticky mucus that interferes with the proper functioning of multiple organs and systems.

The respiratory system is one of the first systems to be affected. As a result, a child with cystic fibrosis can have repeated lung infections. Over time, it may become difficult for them to breathe.

Thickened mucus can also build up in other organs and cause the following problems:

• Preventing the pancreas from sending enzymes that break down food and absorb nutrition to other parts of the body, which causes malnutrition and growth problems
• Allowing the bile ducts around the liver to become blocked, causing liver damage and scarring

Cystic fibrosis typically progresses over time, with becoming more severe as the child gets older.

While in the past most children with cystic fibrosis did not survive into adulthood, this is no longer the case thanks to advances in the screenings, diagnosis, and treatments available. This is increasing cystic fibrosis life expectancy. As a result, children with this disease are living into their 30s, 40s, and beyond.

Diabetes: Cystic fibrosis can lead to diabetes if problems with the pancreas become so severe that some of its cells are destroyed. Cystic fibrosis-related diabetes (CFRD) can lead to glucose intolerance and insulin-dependent diabetes. Up to 20 percent of CF patients develop CFRD in their teens, and 40 to 50 percent develop the disease as adults.

Liver disease: As people with cystic fibrosis live longer, their risk of cystic fibrosis liver disease (CFLD) increases. Symptoms often first become noticeable during puberty. About 30 percent of adolescents with CF develop CFLD. In rare cases, CFLD can lead to cirrhosis.

Infants born with cystic fibrosis typically show signs within the first year. Cystic fibrosis can affect different organs and systems in a number of ways.

Respiratory symptoms of cystic fibrosis

Cystic fibrosis symptoms related to the respiratory system can include:

• Frequent lung and sinus infections
• Chronic cough
• Coughing up blood
• Clubbing (rounding and enlargement of the fingers and toes)
• Heart enlargement
• Nasal polyps (fleshy growths in the nose)
• Sinusitis (inflamed nasal sinuses)

About 10 to 20 percent of children with cystic fibrosis have nasal polyps — small protrusions of tissue from the lining of the nose — that need to be surgically removed. Children with cystic fibrosis also have a high rate of sinus infections.

Digestive symptoms of cystic fibrosis

The pancreas secretes digestive enzymes that break down food and provide nourishment for the rest of the body. In around 90 percent of children with cystic fibrosis, the ducts leading from the pancreas to other organs become blocked. This causes difficulty absorbing key nutrients, including fats, some proteins, and fat-soluble vitamins such as A, D, E, and K.

Because cystic fibrosis is a genetic disease, there are two ways to look at what causes it — how it occurs on the cellular level and how a child inherits CF.

What happens at the cellular level?

As the name implies, a “genetic disease” is caused by something in the body’s genes. Genes are found on chromosomes — structures in the cells that usually come in pairs.

One pair of chromosomes includes a gene called the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This gene is large and complex — in fact, more than 1,000 different CF-related mutations have been identified.

In most people, the CFTR gene helps regulate the flow of salt and fluid in and out of cells. But if there is a mutation in this gene, chloride, a component of salt, gets stuck inside the cells and a thick, sticky mucus starts to build up inside the body.

How cystic fibrosis is inherited

Cystic fibrosis is a genetic disease, meaning it is passed down through the parents. When a baby is born with cystic fibrosis, they have inherited two cystic fibrosis genes, one from the mother and one from the father.

A person with only one cystic fibrosis gene is healthy and said to be a "carrier" of the disease. If both parents carry the cystic fibrosis gene, they each have one copy of the defective gene, but do not have the disease themselves. Their children have a:

• 25 percent chance of inheriting both defective copies and having cystic fibrosis
• 50 percent chance of inheriting one defective copy and being a carrier
• 25 percent chance of not having cystic fibrosis and not carrying the gene

All newborns in Massachusetts — and most other states — are screened for cystic fibrosis. If doctors suspect that a child has this disease, they typically test a sample of the child’s sweat to determine how much salt (sodium and chloride) is in it. A high level of salt indicates cystic fibrosis. The test takes about 40 to 45 minutes from start to finish.

At the present time, there is no cure for cystic fibrosis, but with medical and psychosocial support, many children and adolescents with the disease can cope well and lead a productive life. The goal of treatment is to ease severity of symptoms and slow the progress of the disease.

Cystic fibrosis treatments

Early treatment for cystic fibrosis can improve a child’s quality of life and increase their life expectancy.

A child's treatment is likely to include:

• Chest physical therapy to help loosen and clear lung secretions
• Exercise to loosen mucus, stimulate coughing, and improve overall physical condition
• Medications, such as bronchodilators and anti-inflammatory medications, to reduce mucus and help breathing
• Antibiotics to treat infections
• Management of digestive problems, which may involve appropriate diet, pancreatic enzymes to aid digestion, vitamin supplements, treatments for intestinal obstructions, and dietary supplements
• Ongoing screening to detect early-stage liver disease and intervene as needed
• Psychosocial support to help deal with issues such as body image, feeling different, and managing the condition in a school setting

Managing cystic fibrosis-related diabetes

If a child has cystic fibrosis-related diabetes, they may need to see an endocrinologist in addition to their cystic fibrosis care team. Children with CFRD usually need to be treated with a combination of insulin, diet, and exercise.

Insulin helps glucose enter the cells of the body so it can be used to produce energy. Typically, insulin is injected through a short needle into the fatty layer just under the skin of the belly, leg, or arm.

Children with CFRD should continue to eat a high-calorie diet high in protein and salt, however, they will need to monitor the amount of carbohydrates they eat. Physical activity, such as jogging or playing sports, helps maintain your child’s lung function and regulate blood sugar.

Organ transplant for cystic fibrosis

An organ transplant won't cure cystic fibrosis. However, in severe cases, a transplant may enable a child to live a longer and healthier life.

• Lung transplant — usually a double-lung transplant — may be an option if a child has end-stage lung disease. A lung transplant replaces the diseased lungs with a healthy pair of lungs.
• A child may need a liver transplant if their liver becomes so scarred it can no longer function

Avoiding cross-infection

It’s important for children with a cystic fibrosis diagnosis to stay a minimum of 6 feet away from others with cystic fibrosis. This is because people with this disease are at high risk of spreading dangerous germs to each other. Also known as cross-infection, this can be a very serious concern.

The Cystic Fibrosis Center at Boston Children's Hospital is one of the oldest and largest cystic fibrosis centers in the U.S. We treat more than 600 children and adults each year, providing a broad range of evaluation, diagnosis, treatment, and patient education services.

Our center is staffed by an experienced team of clinicians specializing in the care of patients with cystic fibrosis. As a leading participant in the CF Foundation’s Therapeutics Development Network, we participate in over 50 clinical trials evaluating innovations in cystic fibrosis treatment for safety and effectiveness.