**Core Concept**
Liddle syndrome is a rare genetic disorder characterized by hypertension, hypokalemia, and metabolic alkalosis. It results from mutations in genes encoding for ion transport proteins in the collecting duct of the kidney, leading to excessive sodium reabsorption and potassium excretion.

**Why the Correct Answer is Right**
The correct answer is related to the genetic defect in the ENaC (Epithelial Sodium Channel) complex, specifically in the genes encoding for the subunits alpha, beta, or gamma. This mutation causes an overactive ENaC, leading to increased sodium reabsorption and potassium excretion. The collecting duct cells are unable to regulate sodium and potassium levels properly, resulting in the characteristic symptoms of Liddle syndrome.

**Why Each Wrong Option is Incorrect**
* **Option A:** Mutations in the renin-angiotensin-aldosterone system (RAAS) genes are associated with other forms of hypertension, such as primary aldosteronism or renovascular hypertension.
* **Option B:** Genetic defects in the sodium-potassium pump (Na+/K+ ATPase) are associated with other forms of hypokalemia, such as pseudohypoaldosteronism type 1.
* **Option C:** Mutations in the calcium-sensing receptor (CaSR) are associated with familial hypocalciuric hypercalcemia and neonatal severe primary hyperparathyroidism.

**Clinical Pearl / High-Yield Fact**
Liddle syndrome is often misdiagnosed as primary aldosteronism due to similar presentation, but it is characterized by a lack of aldosterone excess and a specific genetic defect in the ENaC complex.

**Correct Answer: D. ENaC complex genes.**