TNF-alpha Genotype (−857)

If psoriasis or another immune-related disease runs in your family, this result can add a small piece of genetic context. It identifies an inherited DNA difference that researchers have studied in several inflammatory conditions. Its usefulness for predicting your health or choosing treatment remains unproven, even when the DNA result itself is accurate.

The position is called −857 in the control region of the TNF gene, and its identifier is rs1799724. Studies have linked the T version to psoriasis and type 1 diabetes, while some studies of other conditions have reported associations with C. These findings don't establish either letter as a general measure of immune health.

What the Test Reads

TNF-alpha is a signaling protein that helps coordinate inflammation and defend against infection. Excessive TNF activity contributes to tissue damage in several inflammatory diseases. That biological role is well established; the health implications of this particular DNA variant are much less certain.

The promoter is a stretch of DNA that helps control how much protein a gene produces. This test examines position −857 in that region using DNA extracted from cells in your saliva. You inherit one copy from each biological parent, so the usual results are CC, CT, or TT.

Laboratory experiments show that the C-to-T difference can change how regulatory proteins bind to the promoter. Its effects depend on the experimental conditions and nearby DNA differences. Human studies have also reported different relationships between this genotype and TNF production, so a result cannot reliably classify you as having high or low TNF activity.

Psoriasis and Psoriatic Arthritis

Psoriasis is one of the better-studied associations. A 2013 pooled analysis found roughly 50% higher odds of psoriasis or psoriatic arthritis when comparing the T version with C. That estimate came from the studies assessing −857, not every participant in the broader analysis of several TNF variants. A later meta-analysis also associated T with psoriasis, though its results varied by ethnicity, psoriasis type, and study size.

These are comparisons between groups with and without disease. They don't give your lifetime probability of developing psoriasis, and they don't prove that −857 itself causes the difference. TNF sits on chromosome 6 among the HLA genes, which help the immune system tell your own tissue from invaders. The strongest inherited influence on psoriasis is one of those genes, HLA-C*06:02, and variants in this region are often inherited together, so part of the −857 signal may reflect a nearby HLA type.

Type 1 Diabetes

Type 1 diabetes develops when the immune system damages the cells that make insulin. A meta-analysis published online in 2025 and in a 2026 journal issue associated the −857 variant with susceptibility to type 1 diabetes. Its 24 studies covered several TNF positions; they were not all studies of −857. The analysis supports an association, but it did not show that testing this single variant improves screening or predicts who will develop diabetes.

Type 1 diabetes also has its strongest inherited link in HLA genes, specifically the DR and DQ types. Authors of an earlier meta-analysis that associated T with type 1 diabetes noted the finding may reflect linkage with these HLA types rather than an effect of −857 itself.

Gum Disease

Periodontitis damages the tissues and bone supporting your teeth. A Japanese study compared adults with severe periodontitis with healthy controls and found an association with carrying variants at one or more of three TNF promoter positions, including −857. It did not isolate a dependable risk estimate for −857 alone. A separate experiment in healthy volunteers found a tendency toward greater TNF production from stimulated immune cells carrying these variants.

An eastern Indian study associated rs1799724 with chronic periodontitis, but not with the aggressive form studied there. The pooled evidence is weaker than these two studies suggest: a 2020 meta-analysis of 52 studies found no association between −857 and either chronic or aggressive periodontitis. This genotype does not predict recurrence, determine dental care, or reveal whether gum disease is currently present.

Crohn's Disease and Ulcerative Colitis

An early study of 587 families associated CC with inflammatory bowel disease, and healthy people with CC produced more TNF from stimulated cells. In Asian populations the direction appears reversed: a 31-study meta-analysis found T associated with higher Crohn's disease risk there. A New Zealand study reported that carrying T was linked to lower odds of Crohn's disease affecting both the small and large bowel, and of having needed bowel surgery. These were comparisons at one point in time, so they don't show that a genotype changes your future chance of surgery.

Hepatitis B

Results for hepatitis B are inconsistent. A meta-analysis of 19 Chinese studies linked T to a higher chance of clearing the virus without treatment, while a 12-study meta-analysis found no −857 association with infection outcomes. One Chinese study found CC more often in chronic hepatitis B than in asymptomatic carriers, a comparison between different outcomes among people who were all persistently infected. None of this shows that a genotype causes infection or changes who needs hepatitis B screening.

Other Immune Associations

• Myasthenia gravis: a northern Chinese Han study associated CT and TT with myasthenia gravis accompanied by a thymus tumor and with higher serum TNF-alpha. This autoimmune disease causes muscle weakness. The result has not established a screening role for −857.
• Asthma: a meta-analysis reported an association with −857, including in a subgroup the authors classified as Caucasian. Individual studies point in different directions, with some favoring C and others T, so this does not establish a reliable prediction across ancestry groups.
• Acne: one case-control study found the −857 T version more often in people without acne, suggesting a possible protective association in that population. Neighboring promoter positions showed no difference.

Response to TNF-Blocking Drugs

Researchers have studied whether −857 helps explain differences in response to drugs that block TNF. In a study of 70 people with rheumatoid arthritis taking etanercept, T was more common among the strongest responders than among people who failed to reach even a smaller improvement. The estimate was very imprecise, and the association did not remain statistically convincing after accounting for the multiple comparisons.

Later research has found different directions depending on the disease and drug. Psoriasis studies conflict, with one linking CT and TT to better anti-TNF response and another linking C to etanercept response. A 2026 meta-analysis reported better response with C in psoriatic arthritis, based on two studies the authors called exploratory, and a spondyloarthritis meta-analysis found no overall −857 association. A 2024 systematic review of genetic predictors of biologic response also included this variant. None of these findings has produced a validated rule for selecting a drug.

Cancer Risk and Outcomes

A breast cancer meta-analysis found no association with −857. In a North Indian study, −857 alone was also unrelated to whether men had prostate cancer. Within that study, T was associated with features of more advanced prostate cancer, and a combination of nearby variants containing T was associated with cancer susceptibility. A result at −857 alone does not identify that combination. A pooled analysis of two large US cohorts with 2,321 prostate cancer cases found no TNF variant associated with risk after accounting for multiple comparisons.

A separate study of people already diagnosed with head and neck cancers outside the oropharynx found about a 40% higher recurrence rate among those with CC than among T carriers. In a companion study of oropharyngeal cancer, −857 was not associated with recurrence in HPV16-positive tumors. These are findings about prognosis after diagnosis, not evidence that CC increases the chance of developing those cancers, and they have not established a role for −857 in cancer screening or treatment.

Heart Disease

A Korean case-control study found no association between −857 alone and coronary artery disease. A combination of three nearby variants was associated with about twice the odds of disease, but that combination carried the common C at −857 and appeared to be driven by a different position, −238. A 25-study meta-analysis found no overall −857 association with coronary artery disease. This genotype has not been validated for cardiovascular risk assessment.

When Results Can Be Misleading

• Limited coverage: this result describes one DNA position. It doesn't assess the rest of TNF or the many other genes involved in immune disease. CC does not rule out inherited susceptibility.
• Ancestry and nearby variants: the frequency of C and T, and the DNA variants inherited alongside them, differ among populations. An association found in one population may not transfer to another; in Crohn's disease, the version linked to risk differs between European and Asian studies.
• Association versus cause: many findings come from small studies that compared people with and without disease. Linked genetic differences, especially nearby HLA types, population differences, and chance can contribute to an association.
• Consumer reports and DNA strand conventions: raw consumer DNA calls and third-party interpretations may have different validation from clinical testing. The same position can also be written as G/A on the opposite DNA strand. A disagreement needs comparison of the exact variant and reporting convention.
• Uncertain variants on broader panels: a variant of uncertain significance is a DNA change whose medical meaning is unresolved. This targeted C/T result does not interpret rare variants found elsewhere on a larger panel, and those findings should not be assigned the risks reported for rs1799724.
• Inherited versus acquired DNA: a DNA change found only in a tumor does not establish an inherited genotype. After a donor stem-cell or bone marrow transplant, saliva can contain donor DNA, which can complicate identification of your original inherited result.

A One-Time Result

Your inherited genotype is permanent. Diet, medication, stress, and aging don't change it, so an accurate result needs no routine repeat testing. A repeat using another validated method can be useful if the original call was uncertain or conflicts with another reliable result.

Ongoing care follows your symptoms, family history, and any diagnosed condition. This variant does not establish a schedule for CRP, IL-6, TNF-alpha protein, or blood sugar testing. When a family history warrants condition-specific screening, the screening findings determine what needs follow-up.