Earliest presenting feature of cystic fibrosis in neonate is:

Ans: b (Meconium ileus) Ref: Nelson, 18th ed, p. 1807; 17th ed, p. 1440* Presenting feature in new bom is meconium ileus in 15-20% of newborn infants.* Biliary cirrhosis is seen only in 2-3% of patients.* Pancreatic insufficiency is usually seen after 10 years of life.So, among the options provided, most appropriate is meconium ileus.Cystic fibrosis* It is an inherited multisystem disorder of children and adults characterized chiefly by obstruction and infection of airways and by maldigestion and its consequences.* Dysfunction of epithelialised surfaces is the predominant pathogenic feature.* CF is inherited as autosomal recessive trait.* Gene mutation that contribute to the CF syndrome occur at a single locus on the long arm of chromosome 7.Diagnostic criteria for cystic fibrosis1. Presence of typical clinical features (respiratory, gastrointestinal or genitourinary)2. A history of CF in a siblingOR3. A positive newborn screening testPLUSLaboratory evidence for CFTR dysfunction1. Two elevated sweat chloride concentrations obtained on separate daysOR2. Identification of two CF mutationsOR3. An abnormal nasal potential difference measurementIn case of patients with equivocal or frankly normal sweat chloride values the increased potential differences across nasal epithelium can be used for diagnosis. (AIIMS nov 2007)Conditions in which there is elevated sweat chloride other than cystic fibrosis* Untreated adrenal insufficiency* Ectodermal dysplasia* Hereditary nephrogenic diabetes insipidus* Glucose 6 phosphatase deficiency* Hypothyroidism* Hypoparathyroidism* Familial cholestasis* Pancreatitis* Mucopolysaccharoidosis* Fucosidosis* Malnutrition