One in 2,500 people (i.e. one birth every four days) is born with cystic fibrosis, making it the most common incurable, life-limiting disorder in Australia (Better Health Channel 2019).
What is Cystic Fibrosis?
Cystic fibrosis (CF) is a life-limiting genetic condition wherein abnormally thick and sticky mucus is produced, causing complications that predominantly affect the respiratory, digestive and reproductive systems (Better Health Channel 2019).
CF is incurable and shortens life expectancy, however, this has rapidly improved in recent years due to improvements in care. Prior to the 1990s, most people with CF did not reach adulthood (ACI 2016). Now, the average life expectancy is 38 years of age (Healthdirect 2020).
How Does Cystic Fibrosis Affect the Body?
CF occurs due to a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which is responsible for coding the CFTR protein (CFF 2019a).
This mutation causes the CFTR protein - which is responsible for regulating the balance of salt and water on certain body surfaces (such as the lungs) - to behave abnormally. In some cases, the CFTR protein is not produced at all (CFF 2017a).
A normal CFTR protein allows chloride (a salt component) to move from the inside of a cell to the outside, where it attracts water to the cellular surface. This water allows tiny hairs on the cellular surface (known as cilia) to sweep mucus away (CFF 2017a).
However, a defective or absent CFTR protein causes the chloride to become trapped inside the cells, preventing water from hydrating the cellular surfaces. As a result, the mucus dehydrates and becomes thicker. Furthermore, the cilia are weighed down by this thick mucus and are unable to sweep it away, causing it to accumulate (CFF 2017a).
This build-up of mucus is particularly dangerous in the lungs, as it clogs air passages and traps bacteria, leading to frequent blockages and infections. Over time, this may cause permanent lung damage (Better Health Channel 2019).
Accumulated mucus in the digestive system prevents digestive enzymes from being transferred between the pancreas and small intestine, causing issues with digesting fats and absorbing nutrients (Better Health Channel 2019).
How is Cystic Fibrosis Inherited?
CF is an autosomal recessive disease, meaning that it is not possible to inherit CF unless both parents have the defective gene (MedlinePlus 2020; Mayo Clinic 2020a).
A person who inherits only one defective gene (i.e. from only one parent) is a carrier but will not show symptoms, as the normal (unaffected gene) is dominant and will be able to compensate for the defect (Mayo Clinic 2020a; Winikates 2012).
Therefore, if both parents are carriers:
There is a 25% chance that the child will be unaffected
There is a 50% chance that the child will be a carrier
There is a 25% chance that the child will have CF.
(Mayo Clinic 2020a)
If one parent has CF and the other is a carrier:
There is a 50% chance that the child will be a carrier
There is a 50% chance that the child will have CF.
It is estimated that 1 in 25 Australians are carriers. While most carriers are unaware that they have the defective gene, screening services are available (Cystic Fibrosis Australia 2016).
Autosomal recessive conditions like CF can skip generations (Cystic Fibrosis Australia 2013).
Symptoms of Cystic Fibrosis
CF affects the body in a variety of ways and may cause:
A persistent cough that may produce mucus
Frequent lung infections and sinusitis
Muscle cramps or weakness in hot weather due to salt loss in sweat
Difficulty gaining weight
Frequent toilet visits
Bulky, greasy stools
Diarrhoea or constipation
(Better Health Channel 2019; Healthdirect 2020)
Patients with CF often experience acute worsening of respiratory symptoms (known as pulmonary exacerbations (PEx)). PEx episodes often involve symptoms such as increased mucus production, increased coughing and shortness of breath along with a decrease in lung function (CFF 2019b).
Complications of Cystic Fibrosis
People with CF may experience a variety of complications, including:
Recurring lung infections
Pulmonary exacerbations (acute worsening of respiratory symptoms)
Haemoptysis (coughing up blood due to airway damage)
Allergic bronchopulmonary aspergillosis (ABPA) (allergic reaction to fungus in the lungs)
Cardiac failure from lung damage
Cancer of the digestive tract
Diabetes (affecting about 20% of teenagers with CF and 40% of adults with CF)
Distal intestinal obstruction syndrome (DIOS)
Infertility (particularly in males)
Electrolyte imbalances or dehydration
(Mayo Clinic 2020b; NHLBI 2020)
CF gradually damages lung tissue, decreasing lung function. In most cases, death is caused by eventual respiratory failure (Mayo Clinic 2020b).
Diagnosis of Cystic Fibrosis
Between 48 and 72 hours after birth, neonates can undergo a heel prick test to detect CF and other medical conditions. A suspected CF diagnosis can then be confirmed by measuring the infant’s sweat for a high concentration of sodium chloride at about six weeks of age (Cystic Fibrosis Community Care 2019; Healthdirect 2020).
Management of Cystic Fibrosis
CF is incurable and requires intensive management to slow its progression (Better Health Channel 2019).
This may include:
Chest physiotherapy (up to four hours daily in some cases)
A variety of medicines (up to 60 tablets daily in some cases), which may include CFTR modulators, antibiotics and pancreatic enzyme supplements
Inhalation using a compressed air pump and nebuliser
A balanced diet that contains high amounts of protein, fat and kilojoules