Cystic fibrosis (CF) is an autosomal recessive disorder in which there is a mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) causing thick, sticky secreations.
70% of cases are due to a deletion at ΔF5O8 on chromosome 7.
Incidence is 1 in 2500.
Presentation may be:
- Finding at newborn screening
- Guthrie blood spot test, looking for raised levels of trypsinogen
- Meconium ileus (10%)
- Failure to thrive due to pancreatic insufficiency and malabsorption
- Steatorrhoea
- Diarrhoea
- Abdominal distension
- Recurrent respiratory infections
Investigations:
- Diagnosis is confirmed by the pilocarpine sweat test
- >60mmol/l Na/Cl diagnostic, <40mmol/l Na/Cl normal
- PCR can pick up >90% of mutations
- Faecal elastase is a sensitive and specific test to detect decreased exocrine pancreatic function
- Spirometry can be used to monitor disease progress – it shows an obstructive pattern
Features/complications of CF include:
- Chronic pulmonary infection and inflammation
- Bronchiectasis
- Haemoptysis
- Pneumothorax
- Pancreatic insufficiency and malabsorption
- Liver disease
- Chronic sinusitis
- Diabetes (a third of patients by age 30)
- Male infertility (congenital absence of vas deferens)
- Osteoporosis
- Meconium ileus
- Distal intestinal obstruction syndrome
- Rectal prolapse
- Nephrolithiasis
- Finger clubbing
Organisms which cause infections in CF include:
- Pseudomonas
- Burkholderia cepacia
Treatment:
- Enzyme replacement
- Physio to clear airways
- Prompt treatment of infection
- ?heart/lung transplant
Death currently around aged 30 but expected to rise to around 50.
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