Monogenic Kidney Disorders as Hidden Drivers of Electrolyte Imbalance and Hypertension.

Hypertension is the leading modifiable risk factor for cardiovascular disease, stroke, and chronic kidney disease worldwide. Although most cases are essential hypertension, a subset of patients harbors monogenic disorders that disrupt how the kidneys control electrolyte balance and blood pressure regulation. These rare conditions provide important insights into the fundamental physiological mechanisms that link tubular sodium transport, extracellular volume homeostasis, and systemic hemodynamics. The distal nephron is crucial in fine-tuning sodium and potassium balance through tightly regulated transport systems, such as the sodium-chloride cotransporter (NCC) in the distal convoluted tubule and the epithelial sodium channel (ENaC) in the collecting duct. Genetic perturbations of these pathways can markedly disrupt electrolyte balance and blood pressure. Monogenic hypertensive disorders exemplify these mechanisms. Liddle syndrome results from gain-of-function mutations in ENaC subunits, resulting in sodium retention, hypokalemia, and suppressed renin-aldosterone levels. Conversely, Gordon syndrome (pseudohypoaldosteronism type II) is caused by the dysregulation of the with-no-lysine (K) kinase-SPS1-related proline/alanine-rich kinase signaling pathway, resulting in NCC overactivation and the paradoxical concurrence of hypertension and hyperkalemia. Apparent mineralocorticoid excess results from deficiency of 11β-hydroxysteroid dehydrogenase type 2, resulting in the inappropriate activation of the mineralocorticoid receptor by cortisol and subsequent sodium retention. Together, these disorders illustrate how discrete defects in distal nephron transport pathways induce characteristic electrolyte signatures while converging on the shared phenotype of hypertension. Understanding these genetic mechanisms may provide insight into fundamental renal physiology and facilitate the use of precision diagnostic and therapeutic approaches for patients with atypical or treatment-resistant hypertension.