SLC22A6 and chronic kidney disease: Concomitantly, CKD patients exhibit profound downregulation of organic anion transporter OAT1/OAT3 expression within renal and hepatic parenchyma, accompanied by compromised efflux pump BCRP and MRP2/4 functionality, ultimately precipitating catastrophic systemic uremic toxin bioaccumulation (Masereeuw, 2022; Spicher et al., 2025; You et al., 2025).