Variant SLC6A20 affecting neurotransmitter transport contributes towards hyperglycinuria (HG) and iminoglycinuria (IG)

SLC6A20 encodes the sodium- and chloride-dependent transporter SIT1 and mediates the sodium-dependent uptake of imino acids such as L-proline, N-methyl-L-proline and pipecolate as well as N-methylated amino acids and glycine. The human protein is expressed in the intestine and kidney. A common SNP in the SLC6A20 gene, a 596C-T transition that results in a thr199-to-met (T199M) substitution can contribute towards iminoglycinuria (IG; MIM:242600) or hyperglycinuria (HG; MIM:138500). Overall, mutations in SLC36A2 together with polymorphisms in the modifiers SLC6A20, SLC6A18, and SLC6A19 constitute the genetic basis for these phenotypes.

Summary from Reactome (R-HSA-5619101), read 2026-09-23.