What is cystic fibrosis?

Cystic fibrosis is an inherited genetic disorder. It is caused by a gene mutation that causes cells to secrete an abnormally thick and sticky mucus. The mucus interferes with the normal functions of the lungs and airways, and affects other organs of the body including those of the digestive system and the skin. It also makes the affected organs prone to infection. 

Cystic fibrosis appears mainly during childhood and early adulthood. It is a serious medical condition that can lead to premature death. While it cannot be cured, it can be managed successfully with proper treatment.

Digestive system

The series of organs within the body that contribute to the digestion of food. It begins at the mouth and ends at the anus, and includes the stomach, small and large intestines as well as the pancreas, gallbladder and liver.

Genetic

Related to genes, the body's units of inheritance or origin.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Causes

Many organs and tissues of our body have glands that secrete mucus. This watery substance forms layers that keep the linings of our internal organs moist and also helps trap and remove harmful foreign substances and microbes.

In cystic fibrosis a gene called CFTR, which plays a vital role in mucus production, is faulty. The gene makes the CFTR protein, which is essential for balancing the salt concentration in the body's cells. When it does not work properly, the cells that produce the mucus do not secrete enough water, resulting in mucus that is dense, thick and sticky.

This type of mucus clogs up the lungs and makes it hard for them to operate. The mucus can also block tubes in the pancreas, which affects normal digestion. It also provides a rich breeding ground for bacteria, so infections are common.

Cystic fibrosis causes mucus to build up in the airways and pancreas.Cystic fibrosis results in a build-up of thick mucus in organs such as the lungs and pancreas. 

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Pancreas

An organ located behind the stomach that secretes insulin and glucagon into the bloodstream and digestive enzymes into the intestines.

Risk factors

About 70,000 people have cystic fibrosis in the world today. [1] The condition is the most common hereditary disease for people of northern European descent and is uncommon amongst other types of populations. 

Millions of people of northern European ancestry carry a single defective copy of the CFTR gene, without developing cystic fibrosis. The CFTR gene exists as two copies and in these individuals (known as carriers), their second copy is healthy. For an individual to develop cystic fibrosis, two copies of the defective CFTR gene are required. This can occur when two carriers, each with one defective CFTR gene, have a child who inherits two defective genes. The chance of this ocurring is one-in-four.   

 

Recessive inheritance of cystic fibrosis.Parents that carry a defective CFTR gene have a one-in-four chance of having a child with cystic fibrosis. 

1. Cystic fibrosis foundation. Accessed 17 September 2014, from

External link

Types

Cystic fibrosis can appear in many forms. This is because the CFTR gene can have more than 1500 mutations, each with a unique effect on the gene's function. As a result, cystic fibrosis varies between people; it can be mild to severe, and appear in different stages of life. In most people, the effects on the lungs are the most serious, but for some people the digestive system is the most affected.

Digestive system

The series of organs within the body that contribute to the digestion of food. It begins at the mouth and ends at the anus, and includes the stomach, small and large intestines as well as the pancreas, gallbladder and liver.

1. Cystic fibrosis foundation. Accessed 17 September 2014, from

External link

Signs and symptoms

The main signs and symptoms of cystic fibrosis occur in the respiratory and digestive systems.

Signs and symptoms in the respiratory system:

  • Breathing difficulties, such as shortness of breath, wheezing and rapid exhaustion during physical activity;
  • Persistent, nagging coughs;
  • Repeated lung infections, such as pneumonia, and;
  • Sinusitis, bronchitis and other types of inflammation of the airways.

Signs and symptoms in the digestive system

The mucus blocks the pancreatic tubes, preventing the digestive enzymes from the pancreas from reaching the stomach and intestines. These enzymes are necessary for normal digestion. Without this function a range of the following digestion-related conditions can develop: 

Other signs and symptoms

  • Very salty sweat;
  • Metabolic syndromes associated with salt loss;
  • Abnormal heartbeat;
  • Clubbing of fingers - enlarged fingernails and toenails, and;
  • Low fertility in adults, especially men.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Pancreas

An organ located behind the stomach that secretes insulin and glucagon into the bloodstream and digestive enzymes into the intestines.

Clubbing of fingers

An abnormal enlargement of the tips of fingers, or toes, and a change in the angle where the nails emerge.

Wheezing

Breathing with a whistling or rattling sound in the chest.

1. Cystic fibrosis foundation. Accessed 17 September 2014, from

External link

Methods for diagnosis

The diagnosis of cystic fibrosis combines two approaches:

  • Testing for the gene mutations that cause the condition, and;
  • Testing for the clinical signs.

Almost all cases of cystic fibrosis are diagnosed shortly after birth through routine screening. However, some infants show only the milder signs of cystic fibrosis. These signs can be hard to detect early, so clinical testing may be needed.

Genetic tests

Newborns and prospective parents can be checked for the presence of a mutated CFTR gene from a tissue sample. The test can also specify the type of the CFTR mutation present.

Genetic tests for cystic fibrosis include:

Carrier testing

Couples planning a pregnancy, who have family histories of cystic fibrosis, may choose to check whether they are carriers of a mutated CFTR gene. This test is performed on a sample of saliva or blood.

Prenatal screening

If there is a reason to suspect that a fetus might have cystic fibrosis, a doctor can take a sample of the amniotic fluid, using amniocentesis, or the placenta, using chorionic villus sampling.

Newborn screening

In many countries, screening of newborns for cystic fibrosis, and other genetic conditions after birth, is a routine procedure. A small blood sample is taken by pricking the baby's heel which then analysed. 

Clinical tests

Clinical tests assess the impact of cystic fibrosis on the body. These tests can include:

Sweat test 

This is the traditional clinical test for cystic fibrosis. A doctor will induce sweating on a small patch of skin with a weak and painless electrical current, which is then analysed for the salt content.

Sweat test for cystic fibrosis: sweat is collected from a small skin patch and analysed.A sweat test can be used to diagnose cystic fibrosis. 

X-ray testing

An X-ray of the chest can be used to check for lung inflammation and other typical signs of cystic fibrosis.

Other tests

Numerous other tests can be performed depending on the regions of the body that are affected by cystic fibrosis. These can include blood tests, scans and procedures, such as bronchoscopy. 

Genetic

Related to genes, the body's units of inheritance or origin.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

X-ray

A scan that uses ionising radiation beams to create an image of the body’s internal structures.

Amniocentesis

A test performed between 16 and 20 weeks into pregnancy to diagnose genetic abnormalities in the unborn baby, such as Down's syndrome. The test involves removing a sample of (amniotic) fluid around the unborn baby for analysis.

Chorionic villus sampling

A test carried out usually between 10 and 12 weeks of pregnancy on a sample of placenta, to diagnose Down's sydnrome or other genetic abnormalities in the unborn baby.

1. Cystic fibrosis foundation. Accessed 17 September 2014, from

External link

Types of treatment

There is currently no cure for cystic fibrosis. However, recent developments in diagnosis and treatment of the disease mean that people with cystic fibrosis can now enjoy a greatly improved lifespan and quality of life.

Current treatment strategies focus mainly on reducing the production of mucus, preventing infections and managing the nutritional problems that result from having cystic fibrosis.

Treatments for cystic fibrosis include:

Lung and airway treatment

Physical therapy

There are several therapy techniques that can help to physically clear the lungs and airways of the mucus build-up. This is done on a regular basis, usually once a day.

The treatment generally involves a carer or health professional thumping the chest area of the patient in a variety of ways and postures. Breathing exercises are also used, as well as devices that use vibration and air compression to help dislodge and clear mucus from the airways.

Nasal congestion can be cleared with the aid of inhalation, or a gentle flushing of the nasal passages with a salt rinse.

Exercise

Exercise can help to reduce inflammation, encourage air flow and loosen mucus from the respiratory system. Exercise can also maintain healthy function of the joints and muscles of the chest and back, and can improve breathing. 

Medication

Medication to treat respiratory problems in cystic fibrosis can be divided into five categories:

  • Antibiotics - to help fend off bacterial infections of the lungs and airways;
  • Bronchodilators - to widen the airways and help with breathing, such as inhaled salbutamol;
  • Anti-inflammatory medication - to fight inflammation and swelling;
  • Mucolytics - medication to help break down and thin out the mucus, such as nebulised hypertonic saline or inhaled mannitol, and;
  • Gene therapy - a new category of medications is being designed to deal with the root cause of cystic fibrosis, the malfunction of the mutated CFTR gene. The first of these medications, ivacaftor, was recently approved for use. [2]  

Lung transplant

Lung transplantation can sometimes be recommended in cases of severe lung disease. However, this transplantation does not cure cystic fibrosis in other affected organs.

Digestive system treatment

Nutrition

People with cystic fibrosis benefit from a carefully planned diet to help them cope with their impaired digestive system. The increased loss of salt from the body means it is important to keep a close eye on hydration and salt levels, especially during exercise.

Enzyme supplements

Regular supplements of enzymes help to replace the body's own digestive enzymes, which cannot otherwise reach the intestines. These help to offset malnutrition and other symptoms associated with cystic fibrosis.

Nutritional supplements

These are given to replace the nutrients that people with cystic fibrosis do not absorb from their diet. They include electrolyte and vitamin supplements.

Surgery

In some cases of intestinal blockage, surgery may be needed.

Digestive system

The series of organs within the body that contribute to the digestion of food. It begins at the mouth and ends at the anus, and includes the stomach, small and large intestines as well as the pancreas, gallbladder and liver.

Electrolyte

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Respiratory system

The bodily parts comprising mainly the lungs and the airways. Its primary function is the intake and exchange of oxygen and carbon dioxide gases, respectively.

2. Ivacaftor. Medline Plus – U.S. National Library of Medicine. Accessed 22 June 2015, from

External link

Potential complications

Lung complications

Problems with lungs are the main complications associated with cystic fibrosis, causing about 85% of deaths. [3]  The onset of complications occurs over a period of time, as the repeated damage from mucus, inflammation and infections accumulates in the lungs. Some of the complications include:

Digestive system complications

Complications of the digestive system include:

  • Pancreatitis - inflammation of the pancreas;
  • Rectal prolapse - rectal tissue protruding from the anus as a result of extensive coughing and/or problems passing stools;
  • Gallstones;
  • Heartburn, and;
  • Distal intestinal obstruction syndrome (DIOS) - a form of bowel obstruction.

Other complications

As cystic fibrosis progresses over time, it can contribute to several other health problems. These can include:

  • Diabetes - this is a common complication of cystic fibrosis. Up to 15% of teenagers and 50% of adults develop the condition; [4]
  • Bone and joint problems, such as arthritis and osteoporosis;
  • Infertility - individuals with cystic fibrosis can enjoy a normal sex life, however most men are infertile (in about 98% of cases). Fertility in women is more variable, but it is generally lower than the general population;
  • Bowel and urinary incontinence, and;
  • Liver damage.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Digestive system

The series of organs within the body that contribute to the digestion of food. It begins at the mouth and ends at the anus, and includes the stomach, small and large intestines as well as the pancreas, gallbladder and liver.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Nasal polyps

Fleshy outgrowths or lumps from the internal lining of the nose and sinus, often due to allergies, that can cause nasal obstruction and sinusitis.

Pancreas

An organ located behind the stomach that secretes insulin and glucagon into the bloodstream and digestive enzymes into the intestines.

3. Rishishwar L. Varghese N. Tyagi E. et al. (2012) Relating the disease mutation spectrum to the evolution of the cystic fibrosis transmembrane conductance regulator (CFTR). PloS One 7: e42336.

4. Barrio R. (2015) Management of endocrine disease: cystic fibrosis-related diabetes: novel pathogenic insights opening new therapeutic avenues. European Journal of Endocrinology 172: R131–R141.

Prognosis

Until recent times, people with cystic fibrosis were not expected to survive beyond their teenage years. Today, advances in treatment have allowed people with cystic fibrosis to live well into adulthood. The current average life expectancy of people with cystic fibrosis is 38 years.

People with cystic fibrosis can expect to lead a relatively normal life if they follow the nutritional, physical and medication routines described above. Their increased susceptibility to infection means they tend to spend more time in hospital, but they can still continue to study, work and enjoy social and romantic relationships. 

Living with cystic fibrosis can sometimes be emotionally difficult. People with cystic fibrosis are encouraged to share any emotional issues they may have with family, friends and healthcare professionals. They are at increased risk of developing depression

There are dedicated cystic fibrosis support groups, like Cystic Fibrosis Australia, who can provide resources, support and connect you with other people living with the condition. 

3. Rishishwar L. Varghese N. Tyagi E. et al. (2012) Relating the disease mutation spectrum to the evolution of the cystic fibrosis transmembrane conductance regulator (CFTR). PloS One 7: e42336.

4. Barrio R. (2015) Management of endocrine disease: cystic fibrosis-related diabetes: novel pathogenic insights opening new therapeutic avenues. European Journal of Endocrinology 172: R131–R141.

Prevention

Cystic fibrosis cannot be prevented. As a genetic disease, the only preventative measures are screening for the genetic defect, either before conception or before birth.

Genetic

Related to genes, the body's units of inheritance or origin.

3. Rishishwar L. Varghese N. Tyagi E. et al. (2012) Relating the disease mutation spectrum to the evolution of the cystic fibrosis transmembrane conductance regulator (CFTR). PloS One 7: e42336.

4. Barrio R. (2015) Management of endocrine disease: cystic fibrosis-related diabetes: novel pathogenic insights opening new therapeutic avenues. European Journal of Endocrinology 172: R131–R141.