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Frequently asked questions about cystic fibrosis (CF)

    CF is a genetic disease, which means you inherit it from your parents. CF causes your internal organs, especially the lungs and the digestive system, to become clogged with sticky mucus, which can result in infections in the lungs and problems with digesting food.1 

    CF is caused by a faulty gene inherited from both parents. This means that a person with CF is born with the condition and that it is not possible to ‘catch’ it from someone else.1   

    Genes tell the body how to make proteins and where to send them in your cells for them to work. Faulty (or ‘mutated’) genes affect the body’s ability to make or instruct the cystic fibrosis transmembrane conductance regulator (CFTR) protein channels, which is a channel that helps chloride (a part of salt) and water move in and out of cell membranes.2 In people with CF, there are either not enough of these channels or they do not work correctly.3    

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    Proteins are tiny machines that do specific jobs within our cells. The CFTR protein is a particular type of protein called an ion channel. These proteins act like channels or ‘gates’ that open and close to allow water and chloride ions (a part of salt) to move in and out of cells (e.g. in the lungs and pancreas). When the chloride ions are on the outside of the cell, they attract a layer of water, which allows tiny hairs on the surface of the lung cells, known as the ‘cilia’, to sweep mucus up and out of the airways.3  

    In CF, CFTR proteins do not work properly or are too few in number. If CFTR proteins are not working correctly, chloride ions get trapped inside the cell and water is no longer attracted to the outside of the cell. As a result, the mucus in the airways becomes dehydrated and thickens, causing it to flatten the cilia, which are then unable to properly sweep back and forth.3  

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    In the UK, all newborn babies are screened for CF as part of the heel prick test, performed a few days after birth. However, a positive newborn screening result does not necessarily mean that your baby has CF. If a baby is suspected to have CF, a sweat test from the arm or leg will be performed as a follow up to the screening process to confirm they have the condition. The sweat test measures the concentration of chloride (as in salt) in the sweat, which is higher in people with CF than those without it. A genetic test can be performed to check for the faulty gene that causes CF by taking a sample of the individual’s blood or saliva.1,4  

    It is important to mention that the heel prick test screens for the most common mutations, but not all of them. Therefore, it might be possible for someone with a rare genetic mutation not to be diagnosed with CF until later in life through a sweat and/or genetic test.1,4  

    CF is equally common in males and females.5  

    According to the 2020 UK CF Registry report, just under 93% of the CF population in the UK are White, 3% are Asian, approximately 0.2% are Black and just over 1% are Mixed. 5  

    According to the 2020 UK CF Registry report, around 10,800 people in the UK have CF.5  

    CF affects an estimated 105,000 people worldwide (across 94 countries), but the number of babies with CF per babies born varies greatly across the globe.6,7 

    People with CF experience a variety of symptoms including:1 

    • Wheezing, coughing and shortness of breath 

    • Frequent chest infections  

    • Damage to the airways (bronchiectasis) 

    • Difficulty putting on weight and growing 

    • Yellowing of the skin and whites of the eyes (jaundice) 

    • Large, smelly faeces and/or constipation 

    People with the condition can also develop a number of CF-related complications including diabetes, liver problems and infertility. 

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    There are more than 1700 known mutations of the disease.8 The mutations can be split into five different classes depending on how the CFTR protein is affected. Around 85% of people with CF in Europe have a class II mutation, in which the protein does not reach the surface of the cell. The most common class II mutation is F508del.2 

    It is important to know your genotype (the combination of CFTR gene mutations in your DNA) because this may influence the symptoms you experience. 

    People with CF might need more energy (calories) than other people because their body finds it more difficult to digest and absorb nutrients from the food they eat. In particular, sticky mucus in the pancreas prevents enzymes, which are chemicals that help the body break down the  food we eat, from reaching the stomach and properly breaking down the food. The exact amount of calories and fat needed to maintain a healthy weight varies according to age, weight, height, symptoms and activity level. It is important that you consult your doctor, nurse or dietician for specific CF dietary and nutritional advice.9  

    Get inspiration for healthy recipes on CF Kitchen.

    Regular physical activity should be a central part of management for everyone living with CF. Exercise helps with general fitness, health and well-being, and is associated with better long-term outcomes. An active lifestyle can help get mucus out of your lungs and support airway clearance techniques. You can reach out to your CF physiotherapist, doctor or nurse if you have any questions about the type and intensity of exercise suitable for you.10  

    Remember to take special care when the weather is hot and humid. 

    For more information, visit CF Exercise.

    As people with CF now live healthier and more independent lives, many more embark in part- or full-time jobs. According to the 2020 UK CF Registry report, around 65% of adults (16 years or over) who completed the questionnaire were in work or education, with 33% in full-time employment.5 

    When looking for a job, you might want to pay particular attention to the working environment and time off offered by the company. For more information, visit Work life and finances.

      1. Guo et al. J Cyst Fibros 2022;21(3):456–462. 

      2. Swisher AK et al. CPTJ 2015;26(4):85–98.