<prompt> A child is brought to the pediatric OPD with high grade fever of 24 hours duration. History reveals 3 episodes of chest infection and passage of foul smelling stools. The most probable diagnosis is:Cystic fibrosisMaple syrup urine diseaseBilirubin conjugation defectCriggler Najar syndrome  <response>: High grade fever and recurrent chest infection along with passage of foul smelling stools steatorrhea suggests a diagnosis of cystic fibrosis. In cystic fibrosis because of pancreatic exocrine insufficiency, foul smelling stool steatorrhea is common. Cystic fibrosis: Autosomal recessive disease Mutation in cystic fibrosis transmembrane conductor regulator CFTR gene on chromosome 7q There is defective transpo of chloride and not calcium in cystic fibrosis. CFs: Recurrent respiratory infections Azoospermia and infeility Exocrine pancreatic insufficiency causing steatorrhea Recurrent acutechronic pancreatitis Biliary cirrhosis Failure to thrive Salt depletion Vitamin deficiencies 