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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed April 2007

What is the official name of the GLDC gene?

The official name of this gene is “glycine dehydrogenase (decarboxylating).”

GLDC is the gene's official symbol. The GLDC gene is also known by other names, listed below.

What is the normal function of the GLDC gene?

The GLDC gene provides instructions for making an enzyme called glycine dehydrogenase. This enzyme is one of four components (subunits) that make up a large complex called glycine cleavage enzyme. Within cells, this complex is active in specialized energy-producing centers called mitochondria.

As its name suggests, glycine cleavage enzyme processes a molecule called glycine by cutting (cleaving) it into smaller pieces. Glycine is an amino acid, which is a building block of proteins. This molecule also acts as a neurotransmitter, which is a chemical messenger that transmits signals in the brain. The breakdown of excess glycine is necessary for the normal development and function of nerve cells in the brain and spinal cord.

How are changes in the GLDC gene related to health conditions?

glycine encephalopathy - caused by mutations in the GLDC gene

Mutations in the GLDC gene account for about 80 percent of all cases of glycine encephalopathy. More than 40 mutations have been identified in affected individuals. Many of these genetic changes alter single amino acids in glycine dehydrogenase. For example, the most common GLDC mutation in the Finnish population replaces the amino acid serine with the amino acid isoleucine at position 564 in the enzyme (also written as Ser564Ile or S564I). Other mutations insert or delete genetic material in the GLDC gene, or disrupt how genetic information from the gene is spliced together to make a blueprint for producing glycine dehydrogenase.

Some GLDC mutations lead to the production of a nonfunctional version of glycine dehydrogenase, while other mutations reduce but do not eliminate the enzyme's activity. When an altered version of this enzyme is incorporated into the glycine cleavage enzyme complex, it prevents the complex from breaking down glycine properly. As a result, excess glycine can build up to toxic levels in the body's organs and tissues. Damage caused by harmful amounts of this molecule in the brain and spinal cord is responsible for the intellectual disability, seizures, and breathing difficulties characteristic of glycine encephalopathy.

Where is the GLDC gene located?

Cytogenetic Location: 9p22

Molecular Location on chromosome 9: base pairs 6,532,464 to 6,645,692

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The GLDC gene is located on the short (p) arm of chromosome 9 at position 22.

The GLDC gene is located on the short (p) arm of chromosome 9 at position 22.

More precisely, the GLDC gene is located from base pair 6,532,464 to base pair 6,645,692 on chromosome 9.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about GLDC?

You and your healthcare professional may find the following resources about GLDC helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the GLDC gene or gene products?

  • GCE
  • GCSP
  • glycine cleavage system protein P
  • glycine decarboxylase
  • glycine decarboxylase P-protein
  • glycine dehydrogenase (decarboxylating; glycine decarboxylase, glycine cleavage system protein P)
  • HYGN1
  • NKH

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding GLDC?

acids ; amino acid ; breakdown ; dehydrogenase ; disability ; encephalopathy ; enzyme ; gene ; glycine ; isoleucine ; mitochondria ; molecule ; mutation ; population ; protein ; serine ; toxic

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Applegarth DA, Toone JR. Glycine encephalopathy (nonketotic hyperglycinemia): comments and speculations. Am J Med Genet A. 2006 Jan 15;140(2):186-8. (
  • Conter C, Rolland MO, Cheillan D, Bonnet V, Maire I, Froissart R. Genetic heterogeneity of the GLDC gene in 28 unrelated patients with glycine encephalopathy. J Inherit Metab Dis. 2006 Feb;29(1):135-42. (
  • Dinopoulos A, Matsubara Y, Kure S. Atypical variants of nonketotic hyperglycinemia. Mol Genet Metab. 2005 Sep-Oct;86(1-2):61-9. Review. (
  • Gene Review: Glycine Encephalopathy (
  • Kure S, Kato K, Dinopoulos A, Gail C, DeGrauw TJ, Christodoulou J, Bzduch V, Kalmanchey R, Fekete G, Trojovsky A, Plecko B, Breningstall G, Tohyama J, Aoki Y, Matsubara Y. Comprehensive mutation analysis of GLDC, AMT, and GCSH in nonketotic hyperglycinemia. Hum Mutat. 2006 Apr;27(4):343-52. (
  • Nakai T, Nakagawa N, Maoka N, Masui R, Kuramitsu S, Kamiya N. Structure of P-protein of the glycine cleavage system: implications for nonketotic hyperglycinemia. EMBO J. 2005 Apr 20;24(8):1523-36. Epub 2005 Mar 24. (
  • NCBI Gene (
  • Sellner L, Edkins E, Greed L, Lewis B. Detection of mutations in the glycine decarboxylase gene in patients with nonketotic hyperglycinaemia. Mol Genet Metab. 2005 Feb;84(2):167-71. Epub 2004 Nov 23. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: April 2007
Published: February 8, 2016