TNF-alpha Genotype (−308)

Researchers have linked this inherited variant to gum disease, some autoimmune complications, and response to TNF-blocking drugs. The findings differ across diseases and populations. Using the result to predict your own outcome or guide treatment remains exploratory.

This test identifies rs1800629 in DNA collected from a cheek swab. Your result describes an inherited genetic difference, not the amount of inflammation happening in your body today. A technically accurate genotype can still have uncertain medical usefulness.

What the Test Reads

TNF-alpha stands for tumor necrosis factor alpha. It's a protein messenger made by immune cells and many other cells. It helps coordinate responses to infection, promotes fever, and stimulates other inflammatory signals. Excessive or persistent TNF activity can contribute to tissue damage.

The test reads one position in the TNF gene's promoter. The promoter is the stretch of DNA that helps control when a gene turns on. The position is called −308 because it lies 308 DNA letters before the point where copying the gene into RNA begins.

G and A are the two versions at this position. You inherit one copy from each biological parent, so your report reads GG, GA, or AA. G is the more common version, although frequencies differ across populations. Older papers sometimes call the A version TNF2.

Experiments in cultured human cells have found greater gene activity with the A version. In a small study of adults with periodontitis, white blood cells collected from the mouths of GA carriers also released more TNF-alpha without laboratory stimulation. These findings helped establish A's reputation as a high-producing version.

That description doesn't hold consistently in people. Another study found greater TNF gene activity in blood white cells from GG carriers, and a Mexican lupus study also found higher TNF gene activity in GG patients. An ankylosing spondylitis study found no relationship between this genotype and serum TNF concentration, although TNF was undetectable in about two-thirds of its participants. Cell type, stimulation, disease, and other inherited variants can affect the relationship.

A cheek swab collects cells from inside your mouth. For this inherited variant, cheek cells ordinarily give the same genotype as blood or saliva. Studies using those specimens can therefore inform interpretation of this result.

Gum Disease and Other Mouth Conditions

Periodontitis damages the tissues and bone supporting your teeth. A pooled analysis of 46 studies examining several TNF promoter variants linked −308 AA to chronic periodontitis in Asian and European-ancestry populations. It also reported associations between −308 variation and disease then classified as aggressive periodontitis.

Those associations haven't produced a validated way to predict an individual's gum disease or choose a cleaning schedule. A 2025 periodontal consensus concluded that small sets of genetic markers, including commercially available tests, haven't improved susceptibility assessment beyond established risk factors.

Oral lichen planus causes persistent inflammation inside the mouth. In a Thai study, AA was associated with about eleven times the odds of having the condition. But only six participants had AA, so the estimate was highly uncertain and doesn't establish an elevenfold personal risk. A 2012 pooled analysis found no overall association between this variant and lichen planus.

Findings around tooth roots differ from findings about gum disease. A pooled analysis of only four studies found no clear association with apical periodontitis, and the certainty of that result was rated very low; one of the included studies had reported higher odds with AA. A Brazilian study found that A carriers were more likely to show healing of lesions around tooth roots after root canal treatment. These are different conditions, and the result can't be read as a general measure of oral inflammatory risk.

Lupus, Bowel Disease, and Juvenile Arthritis

Studies have examined both disease susceptibility and severity. The evidence doesn't support a general rule that this variant mainly determines how severe an autoimmune disease becomes.

In one Mexican study, people with lupus who carried A had about three times the odds of kidney involvement compared with GG carriers. That finding hasn't held consistently: a larger Mexican cohort of 442 patients and a study from India found no link between this variant and lupus kidney disease. None of this shows that genotype-based monitoring improves kidney outcomes or establishes the risk for someone who doesn't have lupus.

A Romanian study found associations with inflammatory bowel disease complications outside the gut. A carriers had about ten times the odds of these complications in ulcerative colitis and about seven times the odds in Crohn's disease. The estimates came from small subgroups and were imprecise. They describe differences among people already studied, rather than a reliable forecast of your future complications.

A New Zealand study also found A more frequently in ulcerative colitis subgroups with extensive disease or previous bowel resection than in healthy controls. That comparison doesn't establish how well the genotype predicts surgery among people who already have colitis.

In a pediatric study, A carriers with Crohn's disease had higher disease activity and CRP. The same clinical associations weren't found in the children with ulcerative colitis. A separate Portuguese study linked A to more active juvenile idiopathic arthritis, without finding a clear association with developing the disease.

The direction can change in another condition. Among 335 Norwegian adults with ankylosing spondylitis, A was associated with less uveitis and better spinal function. Uveitis is inflammation inside the eye. An A result therefore doesn't identify a consistently more severe inflammatory disease pattern.

Response to Inflammation-Blocking Drugs

TNF inhibitors block TNF activity and are established treatments for several inflammatory diseases. Examples include etanercept, infliximab, and adalimumab, although their approved uses differ. Researchers have studied whether this genotype helps explain differences in treatment response.

A 2026 pooled analysis of 611 people with ankylosing spondylitis or psoriatic arthritis reported better response associated with G. Its roughly fourfold difference in response odds came from comparing G and A allele counts. An allele is one version of a genetic position. That analysis cannot be read as a fourfold advantage for everyone carrying G, because a person with GA carries both versions.

Smaller studies have reported positive findings. A Swiss study of 86 people with rheumatoid arthritis, psoriatic arthritis, or ankylosing spondylitis found better responses among GG carriers. In an Italian study of 97 people with psoriasis, GG carriers were more likely to meet the response criterion after three months of etanercept, although some GA and AA carriers also responded.

Other results conflict. A pooled analysis in European-ancestry rheumatoid arthritis populations found no clear association with response. In the Norwegian ankylosing spondylitis study, genotype didn't predict who went on to start a TNF inhibitor, though that study didn't measure response with a formal scoring system. One analysis reported stronger associations with etanercept response than with infliximab or adalimumab, but it didn't establish that choosing between those drugs using this genotype improves outcomes.

These findings support continued study of the variant as a possible response marker. They don't provide a validated prescribing rule for GG, GA, or AA.

Heart Attack and Stroke

Pooled results conflict. A 2007 analysis of 23 studies, covering about 17,000 participants across heart disease and stroke comparisons, found no clear association with ischemic heart disease. A larger 2017 analysis of 45 articles found a modest one: A carriers had about 18% higher odds than GG. A 2025 analysis linked the variant to acute coronary syndrome, while a 2020 analysis of coronary artery disease found no association. Individual studies have differed too. In a Greek study of 474 adults, A carriers had nearly twice the odds of an acute coronary syndrome after adjustment for other risk factors.

Stroke analyses have also disagreed about the direction of association, with results varying by population and genetic comparison. These findings haven't established a useful way to estimate your cardiovascular risk from this single variant. GG doesn't provide reassurance against heart disease, and GA or AA doesn't establish a need for heart imaging.

Cancer Findings Point in Different Directions

Across 58 studies of digestive cancers, the A version was associated with modestly higher odds overall. The stomach and liver cancer associations were limited to Asian populations. The pooled estimates were based on unadjusted comparisons, so they couldn't adequately account for factors such as smoking or relevant infections.

A separate colorectal cancer analysis found about 46% higher odds for AA compared with GG, a finding that held only in Western populations. It found no clear association for GA. Combining everyone with an A copy can obscure findings limited to the much less common AA group. Other colorectal analyses disagree: one found no overall association and a possible protective effect in Asian groups, while another found an association only in Asian groups.

Other analyses have reported different directions. An analysis of oral cancer and potentially malignant oral disorders linked GG to oral cancer. A breast cancer meta-analysis found no clear association across the full study population, but reported a modest inverse association in European-ancestry groups and higher odds for AA in African-ancestry groups. These subgroup findings don't establish ancestry-specific screening rules.

Research using other genetic variants to estimate lifelong circulating TNF has suggested higher cardiovascular risk and lower risk of some cancers. That research concerns a different genetic estimate of TNF exposure. Its results cannot be assigned to your −308 genotype.

TNF participates in immune responses that differ by tissue and disease. The TNF gene also lies near HLA and other immune genes that can be inherited together. HLA genes help the immune system distinguish between different cells and substances. Some reported associations may reflect these neighboring genes, differences between study populations, or chance. The available findings don't support changing cancer screening because of this result.

Infections, Metabolism, and Mood

• Sepsis: Sepsis occurs when the body's response to infection causes life-threatening organ dysfunction. An earlier analysis of 25 studies linked A carriage to about twice the odds of sepsis, without a clear difference in mortality. Later pooled analyses haven't agreed: a 2017 analysis found modestly higher odds of sepsis and septic shock in European-ancestry but not Asian groups, a 2019 synopsis found stronger associations in Asian groups, and a 2022 analysis found no clear association in either.
• Specific infections: A meta-analysis found higher odds of severe malaria among A carriers in Asian populations, without a clear association in African populations. A small Mauritanian study also found differences between people with chronic hepatitis B and those who had cleared the infection. These findings don't establish individual predictions of infection severity or persistence.
• Metabolic health: A meta-analysis reported different directions of association with metabolic syndrome across ancestry groups. Small studies have also linked A to type 2 diabetes or fatty liver findings. In one fatty liver study, A carriers had more inflammation and scarring, but insulin resistance, rather than genotype, remained associated with these findings in the adjusted analysis.
• Mood and lungs: Individual Thai and Filipino studies found no clear association with major depression and chronic obstructive pulmonary disease, respectively. Those results don't rule out all possible effects in other populations.

When Results Can Be Misleading

• One position only: GG means that A wasn't detected at this position. It doesn't rule out other TNF variants, other inherited influences on inflammation, or inflammatory disease.
• Population differences: Variant frequencies and combinations of nearby inherited genes differ across populations. A finding reported in a broad ancestry group doesn't translate directly into your personal risk.
• Uncertain clinical meaning: GG, GA, and AA describe the DNA result. They aren't diagnoses or severity grades. A variant of uncertain significance reported on a broader genetic panel is a separate issue and shouldn't determine treatment by itself.
• Consumer reports and conflicting calls: Consumer tests may use different coverage and interpretation, and some reports infer variants from nearby markers. A disputed result may need confirmation with an independent clinical method before it is used in a medical decision.
• Inherited versus acquired DNA: Tumor testing can identify DNA changes acquired during life. Those findings aren't automatically inherited. After a donor bone marrow or stem-cell transplant, even a cheek swab can contain donor DNA, so the transplant history matters when planning genetic testing.
• Sample quality: Too few cheek cells or contamination can produce a failed or uncertain call. Collection instructions help prevent these problems.

A One-Time Result

Your inherited genotype at this position is permanent. Routine repeat testing won't show whether inflammation, diet, or treatment has changed. Keep the result with your health records; repeat or confirm it only when the original call is failed, uncertain, or disputed.

Ongoing monitoring follows any condition you have. For example, if you have lupus without known kidney disease, the American College of Rheumatology recommends checking urine protein at least every 6–12 months and during flares affecting other organs. That recommendation applies regardless of this genotype. Established kidney involvement requires a different monitoring plan.

How the Result Fits Into Decisions

GG, GA, and AA are all possible inherited results. None, by itself, establishes a disease, a need for medication, or a schedule of extra screening. Symptoms, family history, examination findings, and disease-specific tests provide the basis for those decisions.

Persistent gum inflammation warrants a dental assessment regardless of genotype. Existing lupus or bowel disease warrants its usual specialist follow-up. A TNF inhibitor should be selected and reviewed according to the condition being treated, safety considerations, and your actual response.

Family conversations can clarify the difference between inheriting A and inheriting a disease. Routine testing of relatives for this variant hasn't been shown to improve care. A genetic counselor can help when a strong family history, unusually early disease, or a broader genetic result raises questions that this single position cannot resolve.