Sepsis is not directly inherited like sickle cell disease or cystic fibrosis, but your genes do influence how likely you are to develop it and how severe it becomes. A landmark Danish twin study estimated that genetic factors account for roughly 40% of the risk of dying from infection, with the remaining variation explained by environmental factors like overall health, age, and exposure to pathogens. That 40% figure makes infectious disease death more heritable than death from cardiovascular disease or cancer, which surprised many researchers when the data first emerged.
So the short answer: sepsis itself isn’t genetic, but your susceptibility to it partly is. Several gene families shape how your immune system detects bacteria, how aggressively it responds, and how quickly it recovers.
How Genes Shape Sepsis Risk
Your immune system relies on a cascade of proteins to recognize invading bacteria and viruses, sound the alarm, and coordinate an attack. The genes that code for these proteins vary from person to person, and those variations can make the difference between a contained infection and one that spirals into sepsis.
One well-studied example involves a receptor called TLR4, which sits on immune cells and detects bacterial components. Certain variants of the TLR4 gene cause your cells to produce more of this receptor, which ramps up the release of inflammatory signaling molecules when bacteria are present. Research on Staphylococcus aureus infections found that people carrying specific TLR4 variants mounted a stronger inflammatory response, even though staph bacteria don’t trigger TLR4 through the usual pathway. This suggests TLR4 plays a broader regulatory role in inflammation than scientists initially thought, and that inherited differences in this single gene can shift the intensity of your immune response to multiple types of infection.
Genome-wide studies have identified dozens of genetic variants linked to sepsis susceptibility. A recent analysis of surgical patients pinpointed variants in genes involved in DNA repair, cell signaling, and protein transport that helped predict who would develop sepsis after an operation. The top three contributing variants sat within genes called PRIM2, RBSN, and SYNPR. While these names won’t mean much outside a lab, the takeaway is significant: genetic differences detectable in a blood sample before surgery could help identify patients at higher risk.
The Cytokine Balance
When infection strikes, your immune cells release cytokines, small proteins that coordinate the body’s defense. In sepsis, this response overshoots. Inflammatory cytokines flood the bloodstream, damaging organs instead of just fighting the infection. Your genes influence how much of each cytokine you produce, and that balance matters enormously.
A large genetic analysis using a technique called Mendelian randomization (which uses inherited gene variants as natural experiments) found that people genetically predisposed to higher levels of a protective molecule called IL-1 receptor antagonist had a 15% lower risk of blood poisoning and a 27% lower risk of streptococcal sepsis. Similarly, those with genetically higher levels of another immune signaling molecule, MIP1α, had a 7% lower risk of sepsis overall and a 35% lower risk of pneumonia-derived sepsis. On the flip side, genetic tendencies toward higher TNF-alpha (a major inflammatory cytokine) were associated with increased risk of streptococcal blood infections.
These findings illustrate something important: it’s not just whether your immune system responds to infection, but how it responds. Some people’s genetic makeup tilts them toward a more balanced inflammatory reaction, while others are predisposed to the kind of runaway inflammation that defines sepsis.
Why Some People Recover and Others Don’t
Once sepsis develops, genetic factors continue to influence outcomes. One critical marker is a molecule called HLA-DR, which sits on the surface of immune cells called monocytes. HLA-DR helps these cells present pieces of bacteria to other immune cells, essentially coordinating the next phase of the defense. When HLA-DR levels drop, the immune system becomes suppressed, leaving the body vulnerable to new infections even as it fights the original one.
A study of over 1,000 septic shock patients found that those with persistently low HLA-DR expression from day three onward had significantly higher mortality and were more likely to develop secondary infections in the ICU. About 55% of patients fell into a “non-improver” group whose HLA-DR levels stayed critically low throughout their hospital stay. This group had the worst outcomes. While HLA-DR expression is influenced by the acute illness itself, baseline genetic differences in HLA genes help determine how quickly and effectively a person’s immune system can rebound.
Children and Adults Differ Genetically
Genetics appear to play a particularly prominent role in pediatric sepsis. Children generally lack the chronic diseases (diabetes, liver disease, heart failure) that predispose adults to severe infections, so when a child develops septic shock, inherited immune factors often carry more explanatory weight.
Gene expression studies in children with septic shock identified a signaling molecule called IL-8 as a key difference between survivors and nonsurvivors. Blood IL-8 levels measured within 24 hours of ICU admission could predict a 95% probability of survival in children receiving standard care. Notably, IL-8 did not predict outcomes with the same accuracy in adults, suggesting that the genetic and molecular pathways driving sepsis severity differ between age groups. Nearly half of children discharged after sepsis were readmitted within a few months (most commonly for respiratory infections), and over 30% of those readmissions occurred in children with no other health conditions, further pointing to underlying immune vulnerability.
Epigenetic Changes From Sepsis Itself
Beyond the genes you’re born with, sepsis can alter how your genes behave going forward. This happens through epigenetic modifications, chemical tags that attach to DNA and turn genes up or down without changing the underlying genetic code. Think of it as the difference between the words in a book and which paragraphs are highlighted.
Research comparing septic and non-septic patients with similar infections found that sepsis was associated with distinct changes in DNA methylation patterns, particularly in immune-related genes. Genes involved in immune cell activation, inflammation control, and organ protection showed altered methylation that correlated with clinical severity scores. These changes help explain why sepsis survivors often remain immunologically vulnerable for months or years afterward. The infection resolves, but the epigenetic marks it leaves behind can keep parts of the immune system dialed down.
Genetic Testing for Sepsis Risk
No genetic test currently exists that can tell you whether you’ll develop sepsis. The condition involves too many genes interacting with too many environmental variables (the type of infection, your overall health, how quickly treatment begins) for a single test to be predictive in a clinically useful way.
However, gene-based diagnostics are entering clinical use for a related purpose: identifying sepsis faster once an infection is underway. The FDA cleared a test in January 2025 that evaluates 29 genes in a blood sample to answer three questions in about 30 minutes: Is there an infection? Is it bacterial or viral? How severe is it? Developed at Stanford Medicine using machine learning, the test identified genes whose activity consistently changes in the same direction across different populations and infection types. This isn’t a genetic susceptibility test, but it uses the body’s gene expression patterns as a real-time readout of what’s happening immunologically.
Researchers have also identified three distinct molecular subtypes of sepsis by analyzing which genes are active in patients’ blood. Published in Nature Medicine in 2025, this framework sorts patients into groups with different inflammatory and immune profiles, each associated with different risks and potentially different treatment needs. The long-term goal is matching patients to therapies based on their molecular subtype rather than treating all sepsis the same way.
Why Treatments Work Differently Across Patients
Genetic variation also helps explain why the same sepsis treatments produce different results in different people. Common ICU medications like vasopressors (which raise dangerously low blood pressure) and corticosteroids (which reduce inflammation) act on receptors and pathways encoded by genes with well-known variants.
For vasopressors like norepinephrine and epinephrine, variants in the genes for adrenergic receptors (the proteins these drugs bind to) can alter how strongly a patient responds. For corticosteroids, at least a dozen known gene variants in the glucocorticoid receptor and related pathways influence drug metabolism and effectiveness. Some patients carry receptor variants that make them more sensitive to steroids, while others carry variants that blunt the drug’s effect. None of these pharmacogenomic insights have yet translated into routine bedside genetic testing in ICUs, but they represent a concrete mechanism by which your DNA shapes not just whether you get sepsis, but how well you respond to treatment if you do.