Common feature of Gitelman syndrome is :
**Core Concept**
Gitelman syndrome is a rare genetic disorder characterized by an imbalance of electrolytes due to mutations in the SLC12A3 gene, which encodes the thiazide-sensitive sodium-chloride cotransporter (NCC) in the distal convoluted tubule of the kidney.
**Why the Correct Answer is Right**
The NCC plays a crucial role in maintaining sodium and chloride balance in the body. Mutations in the SLC12A3 gene lead to impaired sodium reabsorption and increased potassium excretion, resulting in hypokalemia, metabolic alkalosis, and hypomagnesemia. The decreased sodium reabsorption also leads to decreased calcium reabsorption, causing hypocalcemia.
**Why Each Wrong Option is Incorrect**
**Option A:** This is not a characteristic of Gitelman syndrome. Bartter syndrome is a different genetic disorder affecting the thick ascending limb of the loop of Henle.
**Option B:** While hypokalemia is indeed a feature of Gitelman syndrome, it is not the most distinctive or common feature.
**Option C:** This is not a characteristic of Gitelman syndrome. Pseudohypoaldosteronism type 1 is a different genetic disorder affecting the mineralocorticoid receptor.
**Clinical Pearl / High-Yield Fact**
Gitelman syndrome is often associated with a characteristic clinical presentation: hypokalemia, metabolic alkalosis, hypomagnesemia, and hypocalcemia, often accompanied by normal or low blood pressure.
**Correct Answer: B. Hypokalemia**