Identification of novel pathogenic mutations in <i>ATP6V0A4</i> associated with distal renal tubular acidosis and analysis of wild-type expression in glomerular disease

Distal renal tubular acidosis (dRTA) is a rare renal disorder caused by genetic mutations or secondary factors. If untreated, it can result in a significant electrolyte imbalance and progressive chronic kidney disease (CKD). This study investigated the key genes involved in renal tubular acid-base regulation (<i>SLC4A1</i>, <i>ATP6V1B1</i> and <i>ATP6V0A4</i>) through whole exome sequencing (WES) in a clinical cohort. Notably, patients with <i>ATP6V0A4</i> mutations were diagnosed at a younger age (mean 0.5 years) and exhibited more severe renal impairment, including reduced estimated glomerular filtration rate (eGFR), indicating heightened susceptibility to kidney damage. We identified novel <i>ATP6V0A4</i> mutations (c.2219C &gt; T, c.197-1G &gt; C, and c.2293_c.2296del AGCG) and confirmed their pathogenicity using bioinformatics and <i>in vitro</i> experiments. We demonstrated that the c.197-1G &gt; C mutation disrupted mRNA splicing, causing exon 5 skipping and introducing a premature termination codon, c.2293_c.2296del AGCG introduced a premature termination codon, while c.2219C &gt; T impaired protein expression, intracellular pH regulation, and ATPase activity. Additionally, ATP6V0A4 expression decreases during diabetes progression, contributing to tubular dysfunction and the development of diabetic kidney disease (DKD). These findings underscore the crucial role of ATP6V0A4 in maintaining renal acid-base balance, its influence on CKD progression, and the importance of genetic analysis for the early diagnosis and personalized management of dRTA.