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Cystic Fibrosis

  1. Autosomal recessive transmission Q
  2. All the exocrine glands in the body produces abnormal viscid mucus. Q The inspissated secretions obstruct the pancreatic ducts and cause distension of acini which appears like cysts.
  3. Two cardinal symptoms of the disease are chronic diarrhea Q with massive steatorrhea and recurrent respiratory infections. Q
  4. Increased Sweat chloride Q (above 60 meq/1) ***obtained by pilocarpine iontophoresis is suggestive of the diag.
  5. Abnormal Nasal Potential or any two mutant alleles on DNA analysisis also suggestive. 

Cystic fibrosis


Cystic fibrosis (CF) is the most common life limiting recessive genetic disorder in Caucasians with an incidence of approximately 1 in 2500 children born in the United Kingdom. It is less common in African Ameri­cans (1 in 15000) and in Asian Americans (1:31000). It also affects other ethnic groups such as black population with an incidence of 1 in 17,000 and the native American population with an approximate incidence of 1 in 80,000.

The incidence in migrant Indian populations in the UK has been estimated between 1 in 10000 to 12000. The precise incidence of CF among Indians is unknown.

Molecular Genetics


The basic defect in CF is a mutation in the gene for chloride conductance channel, i.e. cystic fibrosis transmembrane conductance regulator (CFTR). The failure of chloride conductance by epithelial cells leads to dehydration of secretions that are too viscid and difficult to clear. The defective gene is located at long arm of chromosome 7. Till now more than 1400 mutations in the gene have been recognized. Commonest mutation is Delta F 508 and constitute upto 70% in Caucasian population. The frequency of mutation in Indian children is 25-30%.


Clinical Manifestations


The clinical features depend on age of diagnosis, suppor­tive care received and treatment. The common clinical presentation includes meconium ileus in neonatal period, recurrent bronchiolitis in infancy and early childhood, recurrent lower respiratory tract infections, chronic lung disease, bronchiectasis, steatorrhea and with increasing age pancreatitis, and azoospermia. Pancreatic insuffi­ciency is present in > 85% of CF patients (Table 13.10).




The diagnosis of CF should be suspected by the presence of a typical phenotype or family history and confirmed by the demonstration of a high sweat chloride (>60 mEq/ L) on at least two occasions and/ or by identifying two CF causing mutations. Nasal potential difference measure­ments can be used as an adjunct to sweat test but is not widely available.




The treatment of cystic fibrosis in children includes respiratory management, nutritional care, anticipation and early diagnosis of liver disease, diabetes and other organ dysfunction.


Respiratory Management


The principle components of care includes airway clearance teclmiques, antibiotics and antiinflammatory agents


Nutritional Management


The main aim of nutritional management is to achieve normal growth and development of children. Nutritional management of CF include:

  1. Increasing caloric intake by encouraging parents to feed the child more frequently. If appetite is poor due to persistent infection, feeding may be given by nasogastric route or by gastrostomy.
  2. Supplement fat soluble vitamins: Due to pancreatic insufficiency, there will be deficiency of fat soluble vitamins. Vitamin A, D and E are supplemented in twice the recommended doses. These should be given along with food and enzymes.
  3. Replace pancreatic enzymes: Enteric coated tablets or spherules of pancreatic enzymes are given with each feed. Enzymes are started at doses of 1000-2000 IV of lipase/Kg in divided doses and modified bsaed on weight gain, nature of stool (frequency, amount and smell) and abdominal symptoms.

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