From the Research
Hyperglycinuria is a rare genetic disorder characterized by excessive amounts of glycine in the urine, primarily caused by mutations in genes responsible for amino acid transport in the kidneys, such as SLC6A18 and SLC6A19, as reported in a recent case study 1. This condition occurs when the kidneys fail to properly reabsorb glycine, an amino acid, from the filtrate during urine formation. There are two main types:
- isolated hyperglycinuria, which affects only glycine transport,
- and generalized aminoaciduria, where multiple amino acids appear in the urine. The condition is often asymptomatic, though some patients may develop kidney stones due to the high concentration of glycine. No specific treatment is typically required for asymptomatic individuals, but those with kidney stones may need increased fluid intake and dietary modifications, as well as regular monitoring of kidney function, to prevent complications such as nephrolithiasis, as seen in a case report 1. Unlike the more serious glycine encephalopathy (non-ketotic hyperglycinemia), hyperglycinuria does not typically affect the central nervous system or cause developmental issues, as it primarily represents a renal transport defect rather than a metabolic disorder, and is distinct from conditions like nonketotic hyperglycinemia, which has been studied in various contexts, including its treatment with sodium benzoate and dextromethorphan 2, 3. Key points to consider in the management of hyperglycinuria include:
- Genetic counseling for affected families
- Regular monitoring of kidney function and urine analysis to detect potential complications
- Increased fluid intake and dietary modifications for patients with kidney stones
- Consideration of the potential for hyperglycinuria to be a marker for other underlying conditions, such as parathyroid adenoma, as reported in a case study 1.