A 7yo is brought by his mother who says that he was well at birth but has been suffering from
repeated chest and GI infections since then. She also says that he is not growing well for this age.
What is the likely condition of this child?
a. CF
b. SCID
c. Primary Tcell immunodeficiency
d. Primary Bcell immunodeficiency
e. Malabsorption
answer: A
Cystic fibrosis
Etiology
• 1 per 3,000 live births, mostly Caucasians
• autosomal recessive, CFTR gene found on chromosome 7 (ΔF508 mutation in 70%, but >1,600
different mutations identified) resulting in a dysfunctional chloride channel on the apical
membrane of cells
• leads to relative dehydration of airway secretions, resulting in impaired mucociliary transport
and airway obstruction
Clinical Presentation
• neonatal: meconium ileus, prolonged jaundice, antenatal bowel perforation
• infancy: pancreatic insufficiency with steatorrhea and FTT (despite voracious appetite), anemia,
hypoproteinemia, hyponatremia
• childhood: heat intolerance, wheezing or chronic cough, recurrent chest infections (S. aureus,
P. aeruginosa, H. influenzae), hemoptysis, nasal polyps, distal intestinal obstruction syndrome,
rectal prolapse, clubbing of fingers
• older patients: COPD, infertility (males), decreased fertility (female)
Investigations
• sweat chloride test x 2 (>60 mEq/L)
= false positive tests: malnutrition, atopic dermatitis, hypothyroidism, hypoparathyroidism, GSD,
adrenal insufficiency, G6PD, Klinefelter syndrome, technical issues, autonomic dysfunction,
familial cholestasis syndrome
= false negative tests: technical problem with test, malnutrition, skin edema, mineralocorticoids
Management
• nutritional counseling: high calorie diet, pancreatic enzyme replacements, fat soluble vitamin
supplements
• management of chest disease: physiotherapy, postural drainage, exercise, bronchodilators,
aerosolized DNAase and inhaled hypertonic saline, antibiotics (e.g. cephalosporin, cloxacillin,
ciprofloxacin, inhaled tobramycin depending on sputum C&S), lung transplantation
• genetic counseling
Complications
• respiratory failure, pneumothorax (poor prognostic sign), cor pulmonale (late), pancreatic
fibrosis with DM, gallstones, cirrhosis with portal HTN, infertility (male)
• early death
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