Abstract
Background and Objectives: Hypocitraturia is a major risk factor for calcium-containing kidney stone disease. Citrate inhibits stone formation by binding calcium in the urine. The SLC13A2 gene encodes the sodium-dependent dicarboxylate cotransporter 1 (NaDC1), a membrane transport protein that facilitates citrate reabsorption in the proximal renal tubules. Variants in this gene, such as rs11568476 (V477M), have been shown to significantly impair transporter activity. This study aimed to investigate the presence of the rs11568476 polymorphism in SLC13A2 and its association with hypocitraturia in Turkish patients with calcium-containing kidney stones. To our knowledge, this is the first genetic study evaluating this polymorphism in a Turkish cohort. Materials and Methods: This prospective cross-sectional study included 90 patients diagnosed with calcium-containing kidney stones at Düzce University Faculty of Medicine, Department of Urology. Based on 24 h urinary citrate levels, patients were divided into two groups: normocitraturic (n = 38) and hypocitraturic (n = 52). Blood and 24 h urine samples were analyzed for biochemical parameters. The rs11568476 polymorphism in SLC13A2 was analyzed using Real-Time PCR. Results: There were no significant differences between the two groups in terms of age, gender, and most biochemical parameters. Serum uric acid levels were significantly higher in the hypocitraturic group (p = 0.002), whereas family history of stone disease was more prevalent in the normocitraturic group (p = 0.024). Genetic analysis revealed no polymorphism in the rs11568476 region; all patients exhibited the homozygous wild-type genotype (GG). Conclusions: No association was observed between the rs11568476 polymorphism and hypocitraturia in this cohort. The absence of the polymorphism suggests that this variant may be rare or absent in the Turkish population. These findings highlight the importance of investigating additional genetic and environmental contributors to hypocitraturia and nephrolithiasis through larger, multicenter studies.