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SAMHD1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SAMHD1 gene

The SAMHD1 gene regulates the availability of dNTP molecules, which are essential for DNA replication and repair, while also helping to control viral infections.

Normal Function

The SAMHD1 gene provides instructions for an enzyme that cleaves deoxynucleoside triphosphates (dNTPs) into their component parts. Because dNTPs are required for both human DNA replication and the replication of viruses like HIV, the SAMHD1 enzyme acts as a regulator to maintain a balance that supports cellular needs while limiting viral spread. Additionally, the enzyme is thought to play a role in DNA repair and the maintenance of genetic stability.

Health Conditions Related to Genetic Changes

Aicardi-Goutières syndrome

Variants in the SAMHD1 gene are associated with Aicardi-Goutières syndrome, a disorder characterized by severe brain dysfunction (encephalopathy) and skin lesions. The condition is linked to the following process:

  • Impaired Regulation: Variants may lead to an enzyme that fails to properly regulate dNTP levels.
  • DNA Damage: Inadequate regulation impairs DNA maintenance, causing damage to accumulate within cells.
  • Immune Response: This accumulated DNA damage may trigger cell signaling that inappropriately activates the immune system. The resulting immune response attacks the body's own tissues, causing inflammatory damage.

Genomic Location

The SAMHD1 gene is found on chromosome 20.

Frequently Asked Questions

Testing usually involves targeted sequencing or a multigene panel that includes SAMHD1. A peripheral blood sample (EDTA tube) is the most common source, but saliva or buccal swabs can be used if blood draw is not feasible. The lab extracts DNA, amplifies the SAMHD1 coding regions, and looks for point mutations, small insertions/deletions, or copy‑number changes.
The first clues often appear in infancy and include irritability, poor feeding, and developmental delay. A characteristic “chilblain‑like” rash on the hands, feet, or ears may develop within the first few months. Later, microcephaly, seizures, or progressive encephalopathy can emerge. Prompt recognition of these signs should trigger neuroimaging and genetic evaluation.
Management is largely supportive. Immunomodulatory drugs such as corticosteroids, JAK inhibitors (e.g., baricitinib), or anti‑IFN‑α antibodies have been tried to dampen the interferon‑driven inflammation. Physical, occupational, and speech therapies address neurodevelopmental delays. Regular ophthalmologic and dermatologic monitoring is advised, and seizure control follows standard protocols. Research into gene‑replacement or small‑molecule modulators of SAMHD1 is ongoing but not yet clinically available.
Yes. SAMHD1 normally depletes intracellular dNTP pools, limiting HIV reverse transcription. Individuals with reduced SAMHD1 activity may have higher dNTP levels, potentially facilitating HIV replication. However, clinical data are limited, and standard antiretroviral regimens remain effective; no specific therapy is currently recommended based on SAMHD1 status.
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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