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GLDC gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GLDC gene

The GLDC gene provides instructions for creating an enzyme essential for breaking down the amino acid glycine, a process critical for normal brain development and nerve cell function.

Overview

The GLDC gene provides instructions for making an enzyme called glycine dehydrogenase. This protein is one of four enzymes that function together as the glycine cleavage system. This system is active within the mitochondria, the energy-producing centers of cells.

The glycine cleavage system breaks down (cleaves) glycine, an amino acid that serves as both a protein building block and a neurotransmitter in the brain. The breakdown of excess glycine is necessary for the normal development and function of nerve cells. Additionally, this process produces a molecule called a methyl group, which is used by folate to support various cellular functions and brain development.

Health Conditions Related to Genetic Changes

Nonketotic hyperglycinemia

Mutations in the GLDC gene are responsible for approximately 80 percent of all cases of nonketotic hyperglycinemia. This condition involves abnormally high levels of glycine in the body, leading to serious neurological issues.

Symptoms and features include:

  • Severe breathing difficulties shortly after birth
  • Weak muscle tone (hypotonia)
  • Seizures
  • Delayed development of milestones

More than 400 mutations have been identified in this gene. Some mutations result in a nonfunctional version of glycine dehydrogenase, while others reduce the enzyme's activity. When the glycine cleavage system is impaired, excess glycine accumulates in tissues and organs, and the production of methyl groups for folate is reduced. It remains unclear exactly how these biochemical abnormalities lead to the specific developmental and neurological features of the condition.

Other Names for This Gene

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

Frequently Asked Questions

Prognosis varies; severe cases may have profound neurodevelopmental delay, while milder forms can achieve limited motor milestones. Ongoing therapy with sodium benzoate, dietary protein restriction, and neurorehabilitation (physical, occupational, speech therapy) can modestly improve function. Early intervention programs are essential.
Both parents should undergo carrier testing for GLDC variants. If both are carriers, each pregnancy carries a 25 % risk of an affected child. Options include prenatal diagnosis (CVS or amniocentesis), pre‑implantation genetic testing with IVF, or using donor gametes. Counseling also addresses recurrence risk, psychosocial support, and available resources.
Many state newborn screening programs include a dried‑blood‑spot assay for elevated plasma glycine or an acylcarnitine profile that flags abnormal glycine metabolism. A positive screen prompts confirmatory plasma and CSF glycine measurements and genetic testing of GLDC.
Immediate treatment focuses on stabilizing breathing (often with ventilatory support), controlling seizures with antiepileptic drugs, and reducing glycine levels using sodium benzoate or dextromethorphan, which inhibit glycine accumulation. Early metabolic specialist involvement improves outcomes.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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