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Condition report · Metabolic

Glutaminase Deficiency

A rare inherited metabolic disorder in which the body cannot properly break down glutamine, an amino acid also used to make brain signalling chemicals. It is caused by changes in both copies of the GLS gene.

A condition report looks for rare variants known to cause the conditions it covers.

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The condition we analyse

Autosomal recessive

Glutaminase deficiency is caused by changes in both copies of GLS, which makes the enzyme that converts glutamine to glutamate.

Signs and symptoms

The most severe form starts soon after birth with seizures, breathing failure and brain abnormalities, and is often fatal in early infancy; blood glutamine levels are raised. Milder forms cause early-onset developmental delay.

What a diagnosis changes

There is no specific treatment; care is supportive, with seizure treatment, breathing and feeding support and developmental care. Genetic counselling is recommended; parents are usually carriers, each future child has a 1 in 4 chance of being affected, and carrier testing can be offered to relatives.

Genes analysed

Includes 2 related subtypes ↓
  • developmental and epileptic encephalopathy, 71
  • spastic ataxia-dysarthria due to glutaminase deficiency
MONDO:0600001Sources: [4][1]

Limitations

  • Expanded repeats in the GLS gene can be hard to detect and size with sequencing, so a negative result does not fully rule out the condition.

References

  1. van Kuilenburg ABP, Mandel H, Moady TA, Sloma R, Fedida A, Leen R et al., 2026. Glutaminase deficiency provides insight to the role of glutamine accumulation and neurotoxicity. Molecular genetics and metabolism
  2. Hujoel MLA, Handsaker RE, Tang D, Kamitaki N, Mukamel RE, Rubinacci S et al., 2026. Insights into DNA repeat expansions among 900,000 biobank participants. Nature
  3. Yau WY, Sullivan R, O'Connor E, Pellerin D, Parkinson MH, Giunti P et al., 2025. Diagnostic yield and limitations of whole-genome sequencing for hereditary cerebellar ataxia. Brain communications
  4. Achanta U, Krishnan S, Chandrasekaran A, Wilson S R, Aiyappan SK, Sundar S, 2024. Neonatal Encephalopathy due to Glutaminase Deficiency in a Neonate. Clinical case reports

Other metabolic conditions

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