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

GPHN gene

The GPHN gene provides instructions for making the protein gephyrin, which is vital for molybdenum cofactor biosynthesis and nerve cell communication.

Normal Function

The GPHN gene provides instructions for making a protein called gephyrin. This protein serves two major functions:

  • Molybdenum cofactor biosynthesis: Gephyrin performs the final two steps in creating molybdenum cofactor. This cofactor is essential for the function of enzymes such as sulfite oxidase, aldehyde oxidase, xanthine dehydrogenase, and mitochondrial amidoxime reducing component (mARC), which help metabolize substances in the body.
  • Nerve cell communication: Gephyrin anchors specific receptor proteins to the correct locations in neurons. This allows neurons to receive signals from neurotransmitters, the chemicals used to relay messages between nerve cells.

Health Conditions Related to Genetic Changes

Molybdenum cofactor deficiency

Mutations in the GPHN gene cause molybdenum cofactor deficiency, a condition characterized by early-onset seizures and progressive brain dysfunction (encephalopathy). This condition is typically fatal by early childhood.

These mutations reduce or eliminate the function of gephyrin, impairing the production of molybdenum cofactor. Without this cofactor, the metabolic enzymes that rely on it cannot function, leading to a buildup of toxic chemicals such as sulfite, S-sulfocysteine, xanthine, and hypoxanthine, alongside low levels of uric acid. The accumulation of sulfite is particularly toxic to the brain, leading to the severe neurological features of the disorder.

Other Names for This Gene

  • GEPH
  • gephyrin isoform 1
  • gephyrin isoform 2
  • GPH
  • GPHRYN
  • HKPX1
  • KIAA1385
  • MOCODC

Frequently Asked Questions

Diagnosis typically relies on newborn screening panels that detect elevated levels of sulfite or S-sulfocysteine in the blood, or low levels of uric acid. Confirmatory testing involves measuring molybdenum cofactor levels in the blood or urine and performing genetic sequencing to identify mutations in the GPHN gene. Early detection is critical because symptoms like seizures and feeding difficulties can appear within the first few days of life.
Parents should seek immediate emergency care if an infant exhibits sudden, uncontrolled seizures, severe lethargy, poor feeding, or vomiting. These symptoms indicate the rapid accumulation of toxic sulfite levels in the brain. Because the condition progresses quickly, any deviation from normal feeding or alertness in a known or suspected case requires urgent medical evaluation to prevent permanent neurological damage.
Currently, there is no cure for molybdenum cofactor deficiency. Treatment is supportive and focuses on managing symptoms, such as using anti-seizure medications to control convulsions. While some patients may receive molybdenum cofactor supplementation, this is generally ineffective for GPHN-related cases because the body cannot properly utilize the cofactor due to the defective gephyrin protein. Management is primarily palliative and aimed at maintaining quality of life.
Yes, if the parents are carriers of the mutation, there is a 25 percent chance with each pregnancy that the next child will be affected. This condition is inherited in an autosomal recessive pattern, meaning both parents must carry one copy of the mutated gene. Genetic counseling is strongly recommended for the family to discuss the risks of future pregnancies and to explore options such as preimplantation genetic testing (PGT) or prenatal diagnosis.
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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