Cystic fibrosis, also known as mucoviscidosis, is an autosomal recessive disorder.1,2,22 It is the most common inherited disease in the Caucasian population affecting 1 in 3000 children in Western Europe.3 It is a multiorgan disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein, which is located on the long arm of chromosome 7 and encodes for a special chloride ion channel.4,5 The vast majority of mutations involve three or fewer nucleotides and result in primarily amino acid substitutions, frameshifts, splice site, or nonsense mutations.11 Of more than 800 identified CFTR mutations, the 3 base pair deletion of phenylalanine at position 508 ...view middle of the document...
Class three mutations, reach the cell membrane but the channel is not properly activated. Class 4 mutations, reach the cell surface and the channel can be activated but have decreased chloride conductance. Class 5 mutations result in decreased abundance of CFTR, as exemplified by incorrect splicing. With some Class 5 mutations a small percentage of correctly spliced mRNA are produced, resulting in a milder phenotype.13
Cystic fibrosis affects the entire body and is age dependant. Symptoms of the disease are shown in the table 1.
Table 1. Signs and symptoms of cystic fibrosis
Lung and sinus disease • clogging and infection of the airways due to inflammation
• persistent coughing
• abundant phlegm production
• decreased ability to exercise
• coughing up blood
• pulmory hypertension
• heart failure
• difficulty getting enough oxygen to body
• blocking of sinus passage
• facial pain
• nasal drainage headaches
• nasal polys
Gastrointestinal, liver and pancreatic disease • Meconium ileus
• Rectal prolapse – caused by increased faecal volume, malnutrition and increased intra-abdominal pressure due to coughing
• Malabsorption malnutrition
• Poor growth and development
• Vitamin A, D, E and K defieciency
• Heart burn
• Intestinal blocking by intussusceptions and constipation
• Distal intestinal obstruction syndrome
• Blocking of bile ducts causing liver damage
Endocrine disease and growth • Diabetes – caused by loss of islets of Langerhans by damaged pancreas.
• Clubbing of fingers – caused by chronic illness and low oxygen (Figure 3).
Infertility • Men make normal sperm but the tube which connects the ejaculatory ducts of the penis to the testes are missing.
• Women are infertile as a result of thickened mucus which interferes with the passage of sperm. In severe cases, ovulation can be disrupted due to malnutrition causing amenorrhea.
The sweat glands, airways, and pancreas are each composed of epithelia and in cystic fibrosis these epithelia have decreased anion permeability.10 The most serious problem facing cystic fibrosis patients is obstruction of the lungs by heavy, thick mucus. As this mucus cannot be cleared effectively, the lungs are highly susceptible to infection by bacteria such as Pseudomonas aeruginosa.8,14 P. aeruginosa produce a number of virulence determinants that give rise to colonization and infection of the respiratory tract which is responsible for their high morbidity and mortality.9,15 Although intensive antibiotic treatment allows 90% of CF patients to survive chronic P. aeruginosa lung infections for more than 10 years, the chronic infection cannot be eradicated by antibiotics.16 Bacterial quorum-sensing influences bacterial behavioural processes such as the ability of bacteria to form biofilms.17,18 Bacteria in biofilms are resistant to disinfectants, antibiotics, and the action of host immune defences....