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GLRA1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GLRA1 gene

The GLRA1 gene encodes a subunit of the glycine receptor, a protein that regulates nerve cell signaling in the spinal cord and brainstem.

Overview

The GLRA1 gene provides instructions for making the alpha (α)1 subunit of the glycine receptor protein. This receptor is embedded in the membranes of nerve cells (neurons) in the spinal cord and brainstem.

The receptor functions as an inhibitory receptor. When the neurotransmitter glycine binds to the receptor, it opens to allow negatively charged chloride ions to enter the neuron. This influx reduces the neuron's ability to transmit signals to other neurons, effectively stopping or inhibiting signaling.

Health Conditions Related to Genetic Changes

Hereditary hyperekplexia

Mutations in the GLRA1 gene can cause hereditary hyperekplexia, a condition most often identified in infants. The condition is characterized by:

  • Increased muscle tone (hypertonia)
  • Exaggerated startle reaction to unexpected stimuli (especially loud noises)
  • Brief periods of rigidity and immobility following a startle reaction
  • Potential breathing cessation in some cases

Mutations in this gene impair the glycine receptor's ability to respond to glycine. Some mutations prevent the receptor from opening, cause it to open inappropriately, or prevent it from reaching the cell membrane. When the receptor is dysfunctional or missing, the resulting imbalance of chloride ions leads to increased cell signaling in the spinal cord and brainstem, causing the abnormal muscle movements and exaggerated startle responses associated with the condition.

Other Names for This Gene

  • GLRA1_HUMAN
  • glycine receptor, alpha 1
  • glycine receptor, alpha 1 isoform 1 precursor
  • glycine receptor, alpha 1 isoform 2 precursor
  • STHE

Frequently Asked Questions

Diagnosis usually begins with a clinical examination noting the characteristic stiffening of muscles and exaggerated startle response to sudden sounds. To confirm the genetic cause, a healthcare provider will order genetic testing, specifically a targeted gene panel or whole exome sequencing, to identify pathogenic variants in the GLRA1 gene. This distinguishes the condition from other causes of infantile spasms or hyperekplexia, such as those involving the SLC6A5 gene.
While there is no cure for the genetic mutation itself, the condition is often highly responsive to clonazepam, a benzodiazepine medication. Clonazepam enhances the activity of GABA, another inhibitory neurotransmitter, which helps compensate for the defective glycine receptors. Many patients experience a significant reduction in the frequency and severity of startle episodes and muscle stiffness when taking this medication, often allowing for normal daily activities.
The most critical risk is apnea, or temporary cessation of breathing, which can occur immediately after a startle response. Caregivers should ensure the infant is always supervised during sleep and wakefulness. Practical management includes minimizing exposure to sudden loud noises, using white noise machines to mask unpredictable sounds, and keeping the infant in a safe, padded environment to prevent injury from sudden stiffening episodes.
Generally, individuals with GLRA1-related hereditary hyperekplexia have normal intelligence and cognitive development. The condition primarily affects motor control and startle reflexes in the spinal cord and brainstem without impairing higher brain functions. However, early and consistent management of the condition is important to ensure normal developmental milestones are met without interruption from severe episodes.
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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