Slc23a3, also known as the orphan transporter SVCT3, is a member of the human SLC23 family. Phylogenetically, this family belongs to the nucleobase-ascorbate transporter (NAT) family, though its nucleobase transport function in humans remains unproven. The SLC23 family is crucial for maintaining physiological vitamin C concentrations, with SVCT1 and SVCT2 being Na(+)-dependent vitamin C transporters. While the exact function of Slc23a3 is not fully clear, genetic models could potentially shed light on its role in biological processes [3,4].

One study confirmed that SLC23A3 is a hypoxanthine transporter in the human kidney. LLC-PK1 renal cells and SLC23A3 RNA-injected Xenopus oocytes showed Na+-dependent hypoxanthine uptake, and specific inhibitors provided further evidence of its role as a hypoxanthine transporter [1]. Genome-wide association studies have associated SLC23A3 with plasma vitamin C levels, schizophrenia, and there are correlations detected with osteoporosis and smoking, suggesting its potential involvement in these areas [2,5,6]. A locus for juvenile myoclonic epilepsy was mapped to a region containing SLC23A3, though no causative variant was detected [7].

In conclusion, Slc23a3 has been identified as a renal hypoxanthine transporter. Its associations with plasma vitamin C levels, schizophrenia, osteoporosis-smoking correlation, and a region related to juvenile myoclonic epilepsy imply its involvement in multiple biological processes and disease conditions. The use of genetic models in future studies could further clarify its functions and contributions to these areas.