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MOCS2 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MOCS2 gene

The MOCS2 gene provides instructions for creating the enzyme molybdopterin synthase, which is critical for the body's ability to metabolize certain substances.

Normal Function

The MOCS2 gene provides instructions for making two proteins, MOCS2A and MOCS2B, which combine to form the enzyme molybdopterin synthase. This enzyme performs a key reaction in the formation of molybdenum cofactor. This cofactor is essential for the function of several enzymes, including sulfite oxidase, aldehyde oxidase, xanthine dehydrogenase, and mitochondrial amidoxime reducing component (mARC). These enzymes help break down (metabolize) various substances in the body, some of which are toxic if not properly processed.

Health Conditions Related to Genetic Changes

Molybdenum cofactor deficiency

Mutations in the MOCS2 gene cause molybdenum cofactor deficiency, a disorder usually fatal by early childhood. It is characterized by seizures that begin early in life and progressive brain dysfunction (encephalopathy).

The mutations involved typically eliminate the function of MOCS2A, MOCS2B, or both, impairing molybdenum cofactor biosynthesis. This leads 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 condition.

Other Names for This Gene

  • MCBPE
  • MOCO1
  • MOCODB
  • molybdenum cofactor biosynthesis protein E
  • molybdopterin synthase catalytic subunit large subunit MOCS2B
  • molybdopterin synthase small and large subunit
  • molybdopterin synthase sulfur carrier subunit
  • molybdopterin synthase sulfur carrier subunit small subunit MOCS2A
  • MPTS

Frequently Asked Questions

The condition typically presents very early in life with severe neurological problems. Parents might notice seizures that begin shortly after birth, along with progressive brain dysfunction, often described as encephalopathy. These symptoms are due to the buildup of toxic substances like sulfite in the brain.
Unfortunately, molybdenum cofactor deficiency caused by MOCS2 gene mutations is a severe disorder that is usually fatal by early childhood. Currently, there is no effective cure or specific treatment that can reverse the neurological damage or prevent the progression of the disease. Management focuses on supportive care to alleviate symptoms.
Molybdenum cofactor deficiency is an inherited condition, meaning it is passed down through families. It is typically inherited in an autosomal recessive pattern. This means that both parents must carry a copy of the mutated MOCS2 gene for their child to be affected. If both parents are carriers, there is a 25% chance with each pregnancy that their child will inherit two copies of the mutated gene and develop the condition, a 50% chance the child will be a carrier, and a 25% chance the child will not be affected and not be a carrier. Genetic counseling can help families understand their specific risks.
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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