SLC6A20 is a sodium- and chloride-dependent membrane transporter that mediates uptake of imino acids including L-proline and N-methylated amino acids, as well as glycine 1. In the brain, SLC6A20 regulates proline and glycine homeostasis, modulating NMDA receptor (NMDAR) currents through glycine transport 2. The transporter is widely distributed across the central nervous, renal, and intestinal systems, where it facilitates amino acid absorption and reabsorption 1. Mutations in SLC6A20 cause iminoglycinuria and hyperglycinuria, metabolic disorders affecting amino acid excretion 1. SLC6A20 variants have been associated with Type 2 diabetes susceptibility across multiple populations, with rs13062383 showing highly significant association 3. Additionally, polymorphisms in SLC6A20 correlate with Hirschsprung disease susceptibility, particularly long-segment forms 4. Clinically, SLC6A20 has emerged as a therapeutic target. The gene maps to the 3p21.31 locus identified in genome-wide association studies of COVID-19 severity with respiratory failure 5, and elevated SLC6A20 expression may increase cancer patients' COVID-19 susceptibility 6. SLC6A20 inhibition shows therapeutic promise for brain disorders involving NMDAR hypofunction, such as schizophrenia 2.