Features of cystic fibrosis –a) Lung nornial at birthb) Abnormal sweat chloride testsc) Autosomal dominantd) Defect in Chromosome 11

Cystic fibrosis (C.F.) is an autosomal recessive disease, where all the exocrine glands in the body especially those in the respiratory & G.I.T. system are involved & produce abnormal visid mucous. The gene is located on the chromosome-7. Most patients with CF present in childhood. Approx 18% of patients present within the first 24 hr of life with Gastrointestinal obstruction, termed Meconium ileus. Other systems dysfunctions are not present at birth, they may manifest within the first year or two of life including respiratory tract system. The diagnosis is confirmed by demonstration of a high sweat chloride (>60 mEq/L) on repeated measurements. Pathophysiology of high sweat chloride Cystic fibrosis patients secrete nearly normal volumes of sweat in the sweat acinus. However, CF patients are not able to absorb NaC1 from sweat as it moves through the sweat duct due to the inability to absorb Cl- across the ductal epithelial cells. This dysfunction in the sweat gland is typically measured by collecting sweat after iontophoresing a cholinergic agonist into the forearm.