Cystic Fibrosis Flashcards

1
Q

Heritability of CF?

A

Autosomal recessive

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2
Q

What is CF caused by?

A

Abnormal gene coding for cystic fibrosis transmembrane regulator protein (CFTR) on chromosome 7

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3
Q

What type of protein is CFTR?

A

cAMP-dependent chloride channel blocker

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4
Q

Most common mutation in CF?

A

^F508 (^ meant to be a triangle)

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5
Q

Pathophysiology of CF?

A

Poor transport of chloride ions and water across epithelial cells of the respiratory and pancreatic exocrine glands result in an increased viscosity of secretions

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6
Q

Presentation of CF? (both adult + neonatal)

A

Adults

  • recurrent chest infections
  • failure to thrive due to malabsorption
  • liver disease

Neonates

  • prolonged neonatal jaundice
  • bowel obstruction (meconium ileus)
  • rectal prolapse
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7
Q

Investigation/diagnostic test for CF?

A

The sweat test

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8
Q

How does the sweat test work?

A

Sweat stimulated by pilocarpine iontophoresis, collected on filter paper, and analysed for NaCl concentration
- the abnormal function of sweat glands in CF results in excess concentration of NaCl in sweat

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9
Q

What are the expected sweat test results for a CF patient and a “normal” patient?

A

CF - NaCl = 80-125mmol/L

Normal - NaCl = 10-14mmol/L

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10
Q

How many times do sweat tests need to be performed and why?

A

At least 2 tests should be performed

- diagnostic errors and false positives are common

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11
Q

Management of CF?

A

Physiotherapy - for respiratory secretions
Antibiotics - for prophylaxis and treatment of lung infections
Pancreatic enzyme supplements - for prevention of malabsorption

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12
Q

Complications of CF?

A
Diabetes
Hepatic cirrhosis 
Male infertility
Severe pulmonary hypertension + cor pulmonale
Chronic lung infections
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13
Q

How are cases of CF identified mostly nowadays?

A

National screening programme assesses immunoreactive trypsin levels (IRT)

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14
Q

How are the levels of IRT changed in CF?

A

IRT increased in CF

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