Cystic Fibrosis

Question 1

What is Cystic Fibrosis?

Answer 1

A mutation in the CFTR gene which leads to chloride transport dysfunction, thick secretions from exocrine glands (lungs, pancreas, skin, reproductive organs) and the blockage of secretory ducts. Recurrent lung infections, clubbing and malabsorptive symptoms are common presentations of CF in children.

Question 2

What is its genetic inheritance pattern?

Answer 2

Autosomal Recessive

1/2500 in the UK

Question 3

What is the pathophysiology of Cystic Fibrosis?

Answer 3

Mutations in the CF transmembrane conductance regulator (CFTR) gene. This gene codes for protein that functions as a chloride channel. This leads to relative dehydration of airway secretions which leads to impaired mucocilliary transport and airway obstruction. It also affects other organ systems including intestine, pancreas and liver.

Question 4

What are the Clinical Features associated with Cystic Fibrosis in neonates?

Answer 4

Meconium ileus
Intestinal Atresia
Hepatitis/Prolonged Jaundice

Question 5

What are the clinical features associated with Cystic Fibrosis in infants?

Answer 5

Rectal Prolapse
Malabsorption + Vitamin deficiency (A,D,E,K)
Pancreatic Insufficiency - Steatorrhoea + Failure to Thrive

Question 6

What are the clinical features associated with cystic fibrosis in older children?

Answer 6

Recurrent Chest Infections (S. aureus, p. aueriginosa, H. influenzae)
"Difficult" asthma
Haemoptysis
Nasal Polyps
Distal Intestinal Obstruction Syndromes
Clubbing of the fingers
Liver Disease
Diabetes Mellitus
Heat Intolerance

Question 7

How do you diagnose a child with Cystic Fibrosis?

Answer 7

• Sweat Chloride Test + Sodium Test - can detect elevated levels of Na and Cl in the sweat
• Genetic Testing - can take blood spot at Day 5 of life to test for an immunoreactive trypsiongen which demonstrates CF which is leading identification of disease prior to onset of clinical disease

Question 8

How do you manage a child with Cystic Fibrosis?

Answer 8

1. Maintain lung function by treating lung infections + removing mucus with physiotherapy
2. Maintain adequate growth and nutrition with high calorie diet, pancreatic enzyme supplements and nutritional supplements
3. Genetic Counselling

Question 9

What is the mneumonic for the presenting signs of a child with Cystic Fibrosis?

Answer 9

CF PANCREAS
C - Chronic Cough & Wheezing
F - Failure to Thrive
P - Pancreatic Insufficiency (malabsorptive symptoms such as steatorrhoea)
A - Alkalosis and Hypotonic Dehydration
N (1) - Neonatal Intestinal Obstruction (meconium ileus)
N (2) - nasal polyps
C (1) - clubbing of fingers (CF is leading cause of clubbing in children in the UK)
C (2) - chest radiograph - hyperinflation, increased pulmonary markings
R - Rectal prolapse
E - Electrolyte elevation in sweat/salty skin
A - Absence/Congenital Atresia of the vas deferens
S - Sputum with Staph/Pseudomonas