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SUOX gene

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

SUOX gene

The SUOX gene provides instructions for making an enzyme that is essential for breaking down sulfur-containing amino acids in the body.

Overview

The SUOX gene provides instructions for making the enzyme sulfite oxidase. This enzyme is responsible for the final step in breaking down sulfur-containing protein building blocks (amino acids) that are no longer needed by the body.

During this process, molecules called sulfites are converted into sulfates through a process known as oxidation, which involves the addition of an oxygen atom.

Health Conditions Related to Genetic Changes

Isolated sulfite oxidase deficiency

At least 27 SUOX gene mutations have been identified in individuals with isolated sulfite oxidase deficiency (ISOD). This is a severe, generally fatal disorder that causes significant brain damage.

  • Mechanism: Mutations impair the function of sulfite oxidase, preventing the complete breakdown of sulfur-containing amino acids.
  • Consequences: Sulfites and other toxic compounds accumulate in the body. The nervous system is particularly sensitive to this accumulation, and the resulting toxicity is believed to cause the brain damage observed in ISOD.

Polycystic ovary syndrome

The SUOX gene is also associated with polycystic ovary syndrome.

Other Names for This Gene

  • sulfite oxidase, mitochondrial

Frequently Asked Questions

Early signs often appear within the first few days of life and include severe feeding difficulties, vomiting, and lethargy. Infants may develop seizures shortly after birth, which are often resistant to standard anti-seizure medications. Other indicators include abnormal eye movements, spasticity (stiff muscles), and a distinctive odor to the urine or sweat due to the accumulation of sulfur-containing compounds. Prompt recognition is vital because the condition is progressive and severe.
There is currently no cure for isolated sulfite oxidase deficiency. Treatment is supportive and focuses on managing symptoms, particularly seizures, although these are often difficult to control. Management may include the use of specific anti-epileptic drugs, nutritional support to ensure adequate growth, and interventions to address complications such as spasticity or respiratory issues. The condition is generally fatal in early childhood, though some individuals survive longer with intensive care.
Research suggests that variants in the SUOX gene may be associated with an increased risk of developing polycystic ovary syndrome. The exact mechanism is not fully understood, but it is hypothesized that subtle changes in sulfite oxidase activity or related metabolic pathways may influence hormonal regulation or insulin sensitivity, which are key factors in PCOS. However, SUOX mutations are not the sole cause of PCOS, which is a complex condition with multiple genetic and environmental contributors.
Both conditions result in the accumulation of toxic sulfites, but they have different underlying causes. Isolated sulfite oxidase deficiency is caused by mutations in the SUOX gene, affecting only the sulfite oxidase enzyme. Molybdenum cofactor deficiency is caused by mutations in genes responsible for producing the cofactor (molybdopterin) required by multiple enzymes, including sulfite oxidase, xanthine dehydrogenase, and aldehyde oxidase. Consequently, molybdenum cofactor deficiency often presents with additional symptoms related to the other affected enzymes, such as elevated uric acid levels, whereas isolated sulfite oxidase deficiency primarily presents with neurological symptoms due to sulfite toxicity.
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.