L17 - Cystic Fibrosis Flashcards
Genetics: CF is….
Autosomal Recessive
CF arises from…
- Mutation affecting gene in long arm of chromosome 7.
- Gene coding for chloride channel
- known as cystic fibrosis transmembrane conductance regulator. CFTR
Genetic defect of the CFTR gene will cause?
- Increase in Na+ and Cl- content in sweat.
- Increased resorption of Na+ and water from respiratory epithelium.
How may CF lead to bronchectasis?
- Dehydration of airway epithelium is thought to predispose
- to chronic bacterial infection
- and ciliary dysfunction.
Describe how a CFTR channel works?
- Chloride channel on apical membrane
- controlled by cAMP
- indirectly controlled by B adrenoreceptor stimulation
- Mutation in CFTR leads to absent or defective function Cl- channel
- leads to reduced chloride secretion
- excessive sodium resorption
- dehydration of airway lining
Neonatal screening for CF involves?
- Immunoreactive trypsin
- Genetic testing of newborn blood sample
Children with CF will have their lungs commonly infected with…
Staph. aureus
Adults with CF will commonly have their lungs infected with…
P. Aeruginosa
Gram negative bacilli
Stenotrophomonas
Why are most men with CF infertile?
- Failure of development of vas deferens.
- Seminal vesicular dysfunction
- means that ejaculates are low in volume.
State some respiratory complications of CF
- Progressive airway obstruction
- infective exacerbation of bronchiectasis
- respiratory failure
- spontaneous pneumothorax
- haemopytsis
- lobar collapse due to secretions
- pulmonary hypertension
- nasal polyps
GI complications associated with CF
- Malabsorption
- Steatorrhoea
- Distal intestinal obstruction syndrome
Hepatic complications associated with CF
- Biliary cirrhosis
- progressive destruction of bile ducts of liver - Portal hypertension
- increases BP within portal venous system - Varices
- enlarged veins - Splenomegaly
- enlarged spleen
5.Gallstones
Other complications associated with CF
- Diabetes! –> 25% patients with CF often require insulin therapy.
- Delayed puberty
- Male infertility
- Osteoporosis
- Arthropathy –> inflammation of joints
- Cutaneous vasculitis –> vasculitis affecting vessels in skin and subcutaneous tissue but not internal organs.
Treatment / management of CF
- Daily chest physiotherapy - for patients producing sputum.
- Staph aureus infection managed: oral antibiotics
- Psuedomonas infection: IV treatment
- Patients with coexistent asthma: inhaled bronchodilators and glucocorticoids
Many patients with CF will eventually be colonised by antibiotic resistant bacteria.
How might malabsorption due to CF be treated?
- Due to exocrine pancreatic failure.
- Treated with oral pancreatic enzyme
- vitamin supplements.
Describe role of CFTR potentiators and give an example
Small molecules to correct function of particular CFTR channel.
e.g. Ivacaftor