False about Barter’s syndrome
**Core Concept**
Barter's syndrome, also known as pseudohypoaldosteronism type 1, is a rare genetic disorder characterized by an inability of the kidneys to respond to aldosterone, a hormone that regulates sodium and potassium levels in the body. This leads to an imbalance in electrolytes, particularly hypokalemia (low potassium levels) and metabolic alkalosis.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of Barter's syndrome, which involves a defect in the sodium-potassium-chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle. This defect impairs the reabsorption of sodium, potassium, and chloride ions, resulting in hypokalemia and metabolic alkalosis. The kidneys compensate for this by increasing sodium reabsorption in the distal tubules, leading to hypertension.
**Why Each Wrong Option is Incorrect**
**Option A:** Barter's syndrome is caused by a defect in the mineralocorticoid receptor. **This is incorrect because Barter's syndrome is caused by a defect in the sodium-potassium-chloride cotransporter (NKCC2), not the mineralocorticoid receptor.**
**Option B:** Barter's syndrome is characterized by hyperkalemia. **This is incorrect because Barter's syndrome is actually characterized by hypokalemia, not hyperkalemia.**
**Option C:** Barter's syndrome is associated with hypotension. **This is incorrect because Barter's syndrome is actually associated with hypertension, not hypotension.**
**Option D:** Barter's syndrome is caused by a mutation in the SLC12A1 gene. **This is incorrect because while mutations in the SLC12A1 gene can cause Barter's syndrome, it is not the only cause of the disorder.**
**Clinical Pearl / High-Yield Fact**
A key feature of Barter's syndrome is the presence of hypokalemia, which can lead to muscle weakness, fatigue, and cardiac arrhythmias. It is essential to recognize this condition and initiate treatment promptly to prevent long-term complications.
**Correct Answer:** D.