Molecular Genetics of Bartter Syndrome: Bridging Genotype-Phenotype Correlations and Precision Therapeutics.

Bartter syndrome (BS) represents a group of rare, autosomal recessive renal tubular disorders characterized by hypokalemic hypochloremic metabolic alkalosis, secondary hyperaldosteronism, and normal to low blood pressure. The underlying pathophysiology is primarily driven by defects in critical ion transport proteins or channels localized within the thick ascending limb of the loop of Henle, leading to impaired salt reabsorption. Recent advances in molecular genetics have refined the classification of Bartter syndrome. Current evidence supports SLC12A1, KCNJ1, CLCNKB, BSND, and MAGED2 as the core disease genes within the contemporary BS spectrum, with MAGED2 causing a distinct X-linked transient antenatal form. In contrast, gain-of-function CASR variants, historically labeled "type V Bartter syndrome", are now more appropriately described as CaSR-associated Bartter-like phenotypes within the broader spectrum of disorders of calcium homeostasis. Despite significant progress, two primary research limitations remain. First, fully elucidating genotype-phenotype correlations and overcoming diagnostic complexities continues to be highly challenging due to substantial phenotypic overlap and genetic heterogeneity. Compounding these diagnostic hurdles is the equally critical challenge of understanding mutation-driven pathogenic mechanisms to develop viable clinical interventions. This review systematically summarizes the current molecular genetic landscape of BS to address these gaps. We highlight the relationships between specific genetic variants and clinical manifestations, delve into molecular pathophysiology including protein misfolding and trafficking defects, and explore emerging therapeutic approaches such as molecular chaperones. By integrating genetic and clinical data, this work aims to provide a comprehensive framework to facilitate precise diagnosis and individualized treatment strategies, ultimately advancing precision medicine in the management of Bartter syndrome.