<prompt> Chloride receptor defect is responsible for:Cystic fibrosisWilsons diseaseAlpha-1 antitrypsin deficiencyHemochromatosis  <response>: Ans: A Cystic fibrosis Ref: Harrisons 18th edn, pg 2149Explanation:Cystic FibrosisAutosomal recessiveMutation in CFTR cysic fibrosis transmembrane conductance regulator geneClinical FeaturesBronchiectasisExocrine pancreatic insufficiencyIntestinal dysfunctionAbnormal sweat gland functionUrogenital dysfunctionCF airway epithelia exhibit abnormal Cl- secretion and Na absorptionPredisposes to infections. Staph, aureus. Pseud.aeruginosa. Others are H.influenza. Alcaligenes. Burkholderia, Proteus. E.coli, Klebsiella, AspergillusLack of CFTR Cl- channel in the apical membrane of pancreas, failure to secrete NaHCO3 and water, destruction of the pancreasIn the sweat glands, inability to absorb Cl- from the sweat leads to high Cl- concentrations in sweat measured after iontophoresis of cholinergic agentsSpirometry: RVTLC, FVC and FEV1CXR- hyperinflation, brochiectasis, right upper lobe Earliest involvedClubbing, pneumothorax, hemoptysis, corpulmo- naleGIT: Meconium ileus, DIOS, protein and fat malabsorption, diabetes laterGUT: Late onset puberty, azoospermia, female infertility- TreatmentGene therapy of CFTR geneClearance of secretions with hypertonic saline, antibioticsRecombinant human DNAse to degrade DNA in sputumPancreatic enzyme replacement, Vit E and K. InsulinMegalodiatrizoate enema for acute intestinal obstructionUrodeoxv cholic acid for cholestatic liver diseasePredisposed to renal stones and osteoporosis 