<prompt> False about cystic fibrosis: PGI June 2009Associated with CFTR geneAutosomal recessive inheritanceAssociated with 7p chromosomeRecurrant respiratory tract infection  <response>: Ans: C Associated with 7p chromosome Ref: Robbins 7 th490-95The primary defect in cystic fibrosis results from abnormal function of an epithelial chloride channel protein encoded by the cysticfibrosis transmembrane conductance regulatorCFTR Q gene on chromosome band 7q31.2Q-Robbins 7th490Cystic Fibrosis MucoviscidosisAutosomal recessive? inheritanceAppear at any point in life from before birth 9 to much later in childhood or even in adolescenceMay leads to chronic lung disease1, pancreatic insufficiency ., steatorrhoea-, malnutrition, hepatic cirrhosis, intestinal obstruction male infertility.In sweat glands duct, ENaC Epithelial sodium channel activity decreases as a result ofCFTR mutation; therefore a hypertonic luminal fluid containing both high sweat chloride the sine qua non of classic CF high sodium content is formed .This is the basis of the salty sweat; the mothers can often detect in their affected infant-Robbins7th490Biochemical studies indicate that the F5JH mutation- leads to improper processing and intracellular degradation of the CFTR protein. Thus, absence of CFTR in the plasma membrane is central to the molecular pathophysiology of the F508 mutationCF patients exhibit a characteristic sputum microbiology. Haemophilus influenzae Q and S. aureus are often the first organisms recovered from lung secretions in newly diagnosed patients with CF. P. aeruginosa, often mucoid and antibiotic-resistant, is typically cultured from lower respiratory tract secretions thereafter. Burkholderia formerly Pseudomonas cepacia is also recovered from CF sputum and is pathogenicDiagnostic biophysical hallmark of CF is the raised transepithelial electric potential difference detected in airway epitheliumLate onset of puberty is common in both males and females with CF 