This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Renal physiology, Subject name: Physiology
Liddle syndrome is caused by a genetic defect in 
Select and explain. 
A. Na-K-2Cl co-transpoer in the thick ascending limb of loop of henle, B. Na-Cl cotranspoer in the distal tubule, C. ENasodium Channel in collecting duct/tubule, D. The aquaporin 2 (AQP2) channel in collecting duct
C: ENasodium Channel in collecting duct/tubule
Answer: C: ENasodium Channel in collecting duct/tubule 
Explanation: Liddle syndrome is caused by hyperactivity of the Amiloride-sensitive sodium channel (ENaC) of the principal cell of the coical collecting tubule. Liddle syndrome is a rare autosomal dominant disorder of renal epithelial transpo that clinically resembles primary aldosteronism with hypeension and hypokalemia metabolic alkalosis and with low plasma renin and aldosterone levels. Bater syndrome (Mimics loop diuretics) Gitelman&;s syndrome (MImics Thiazide Diuretics) Liddle Syndrome (Mimics Primary Aldosteronism) Autosomal recessive disorders Autosomal recessive disorder Autosomal Dominant Genetic defect in the thick ascending limb of loop of henle Defects in Na-K-2Cl co-transpoer , K or Cl channels result in lack of concentrating ability Genetic defect in the distal tubule Defect in Na-Cl cotranspoer in the distal tubule Genetic defect in the collecting tubule Caused by hyperactivity of the Amiloride-sensitive sodium channel (ENaC) of the principal cell of the coical collecting tubule Presentation Diagnosis Hypokalemic- Metabolic acidosis with Hypeension Liddle&;s syndrome Hypokalemic Metabolic Alkalosis without hypeension Bater syndrome (Increased urinary Ca Excretion) Gitelman&;s syndrome (Decreased Urinary Ca Excretion) Ref: Ganong