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

SEPSECS gene

The SEPSECS gene provides instructions for making the enzyme SepSecS, which is essential for the production of selenocysteine and the formation of functional selenoproteins.

Normal Function

The SEPSECS gene provides instructions for making an enzyme known as SepSecS. This enzyme is involved in the formation of a specific transfer RNA (tRNA) required to build selenocysteine (Sec), an amino acid containing the essential nutrient selenium. Proteins that contain selenocysteine are called selenoproteins.

There are approximately 25 human selenoproteins with diverse functions, including:

  • Antioxidant reactions: Protecting cells against reactive oxygen species that can damage DNA and cell membranes.
  • Hormone regulation: Activating thyroid hormones.
  • Immune and reproductive function: Supporting the immune system and sperm cell production.
  • Neurological health: Supporting normal brain development and nerve cell (neuron) function.

Health Conditions Related to Genetic Changes

Pontocerebellar hypoplasia

Mutations in the SEPSECS gene have been identified in people with a disorder of brain development called pontocerebellar hypoplasia, specifically pontocerebellar hypoplasia type 2 (PCH2), also known as PCH2D or progressive cerebellocerebral atrophy (PCCA). Major features include:

  • Delayed development
  • Problems with movement
  • Intellectual disability

The mutations that cause PCH2D completely eliminate the function of the SepSecS enzyme, impairing the production of selenocysteine and the subsequent formation of selenoproteins. Researchers are currently investigating how this shortage of proteins leads to abnormal brain development.

Other Names for This Gene

  • liver-pancreas antigen
  • LP
  • O-phosphoseryl-tRNA(Sec) selenium transferase
  • PCH2D
  • SLA
  • SLA-p35
  • SLA/LP
  • SLA/LP autoantigen
  • soluble liver antigen
  • soluble liver antigen/liver pancreas antigen
  • tRNA(Ser/Sec)-associated antigenic protein
  • UGA suppressor tRNA-associated protein

Frequently Asked Questions

Confirmation requires DNA sequencing of the SEPSECS gene to identify pathogenic variants. In addition, functional tests such as measuring selenoprotein activity or selenium levels in blood can support the diagnosis, but the definitive test is genetic sequencing.
Because the defect lies in the enzyme that incorporates selenium into proteins, simply increasing selenium intake does not restore selenoprotein synthesis. In fact, high selenium can be toxic. Therefore, routine selenium supplementation is not recommended unless a deficiency is documented and the patient is under specialist supervision.
Common early signs include developmental delay, motor coordination problems, speech difficulties, and signs of intellectual disability. In some cases, infants may show feeding difficulties or poor muscle tone. If multiple symptoms are present, a neurologist may consider genetic testing for SEPSECS.
Currently, there is no cure that restores the missing enzyme. Management focuses on supportive care: physical, occupational, and speech therapy to improve motor skills; educational support for learning challenges; and monitoring for complications such as seizures or respiratory issues. Research is ongoing into gene‑replacement strategies and small‑molecule chaperones that might stabilize the enzyme.
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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