Nonketotic hyperglycinemia (glycine encephalopathy): laboratory diagnosis.

Abstract

Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder of glycine metabolism caused by a defect in the glycine cleavage enzyme complex (GCS). GCS is a complex of four proteins encoded on four different chromosomes. In classical neonatal NKH, levels of cerebrospinal fluid (CSF) glycine and CSF/plasma glycine ratio are very high but the CSF results, in particular, may be more difficult to interpret in later-onset, milder, or otherwise atypical NKH. Enzymatic confirmation of NKH requires a liver sample. Delineation of which protein of the complex is defective is necessary to screen for mutations in the appropriate gene. Except for Finnish NKH patients, few recurrent mutations have yet been found, although analysis of the P-protein gene (the site of the defect in the majority of patients) is at an early stage. Prenatal diagnosis by GCS assay in chorionic villus biopsies is not completely reliable and will be replaced by molecular analysis in families where the mutations are known.

• Authors: D A Applegarth, J R Toone
• Journal: Molecular genetics and metabolism (Mol Genet Metab) 2001 Sep-Oct Vol. 74 Issue 1-2 Pg. 139-46 ISSN: 1096-7192 [Print] United States
• PMID: 11592811 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Review)
• Copyright: Copyright 2001 Academic Press.

Chemical References

• Glycine

Topics

• Animals
• Female
• Fetal Diseases (blood, diagnosis, enzymology, genetics)
• Genetic Carrier Screening
• Glycine (blood, metabolism)
• Humans
• Hyperglycinemia, Nonketotic (blood, diagnosis, enzymology, genetics)
• Liver (enzymology)
• Metabolism, Inborn Errors (blood, diagnosis, enzymology, genetics)
• Molecular Diagnostic Techniques (methods)
• Pregnancy
• Prenatal Diagnosis (methods)