Definition A banal inborn error of amino acid transport (OMIM:138500) characterised by excess glycine in the urine, which may be associated with renal colic due to oxalate stones.
Molecular pathology Defects of
• SLC6A19, which encodes a protein that actively transports neutral amino acids–especially leucine, across the apical membrane of intestinal and renal epithelial cells,
• SLC6A20, which encodes a transporter that mediates the uptake of glycine as well as imino acids, and
• SLC36A2, which encodes a pH-dependent proton-coupled amino acid transporter that primarily transports small amino acids–e.g., glycine, alanine and proline,
All cause hyperglycinuria
Synonyms Glycinuria with or without oxalate nephrolithiasis, glycinuria with or without oxalate urolithiasis, iminoglycinuria type II