Interleukin 1 Composite Genotype

Two people can brush the same, floss the same, and end up with different gums by age 50. One reason may be written into their DNA. The IL-1 composite genotype is a saliva-based genetic test that reads inherited variants in the IL-1 gene cluster, a stretch of DNA that helps set how strongly your immune system responds to bacteria and tissue injury.

In European-heritage cohorts, about 30% to 40% of adults carry the classic IL-1 positive pattern, though published estimates across white cohorts span roughly 10% to 46%, and prevalence is much lower (about 6% or less) in Asian populations. Some cardiovascular studies use a broader three-variant IL-1(+) grouping; in one catheterization cohort, about 6 in 10 patients fell into that group. Those are not the same claim. The result tells you which inherited pattern the lab found, not whether inflammation is high today.

What This Test Actually Measures

The classic periodontal composite looks for specific variants at IL1A -889 (rs1800587), often reported alongside IL1A +4845 because the two track closely, and IL1B +3954 (also reported as +3953). These genes sit in the IL-1 cluster on chromosome 2 and code for IL-1 alpha and IL-1 beta, proteins that turn inflammation on.

Most commercial periodontal IL-1 tests call the result positive when you carry at least one variant copy at both spots. Some cardiovascular papers define IL-1(+) with a broader three-SNP grouping in IL1A and IL1B. When a study used that broader definition, this article says so.

Saliva is used because cheek cells carry your inherited DNA. For this kind of test, saliva, buccal swab, and blood all point to the same inherited genotype when the sample is clean. Your result at 40 should match your result at 4 or 84.

The test does not measure IL-1 beta protein in saliva or blood. Protein levels rise and fall with infection, dental inflammation, and recent procedures. Genotype is the setting you start with.

Periodontal Disease and Tooth Loss

This is where the two-variant test has the most human evidence. In a 14-year study of 42 periodontal maintenance patients, being IL-1 positive raised tooth-loss risk by about 2.7 times. Heavy smoking raised it by about 2.9 times. Together, the two raised it by about 7.7 times. The study was small, but the interaction was big enough to change how you think about a smoker with active gum disease.

Other studies fit the same pattern: the genotype matters most when something else is pushing the gums. In a five-year European-heritage cohort, IL-1 positive smokers and IL-1 positive people with Porphyromonas gingivalis in plaque had more sites with deeper pockets. In a population study of 1,085 adults, IL-1 positive nonsmokers looked like genotype-negative nonsmokers, while smoking plus IL-1 positivity carried higher periodontitis risk.

Downstream protein studies are useful, but they are not the same test. In a small experimental gingivitis study, IL-1 positive participants had higher salivary IL-1 beta at the end of the plaque challenge and after hygiene was restarted, even though standard gum scores did not differ by genotype. In a Japanese chronic periodontitis cohort, carriers of an IL1A variant, a related but narrower result than the full composite, did not show the same drop in salivary AST and ALT after scaling that non-carriers did.

The mixed periodontal verdict matters. A 2007 systematic review found too little evidence to use the composite genotype by itself to predict progression or treatment response. A later meta-analysis in white adults found only a modest association for the composite genotype (odds ratio about 1.51, with IL1A alone about 1.48 and IL1B alone about 1.54). Use the result as a risk modifier: strongest when smoking, harmful plaque bacteria, bleeding, pocketing, or prior bone loss are already present.

Coronary Artery Disease in Younger Adults

The heart evidence is thinner and it does not always use the exact same genotype definition. In a study of 499 patients getting coronary angiography, researchers used a broader three-variant IL-1(+) grouping tied to higher inflammatory output. Among IL-1(+) patients, the top quarter for oxidized phospholipids on ApoB had about 2.8 times the odds of obstructive coronary disease than the bottom quarter. In patients 60 or younger, the estimate was about 7 times. The single strongest signal in that paper was for Lp(a): in IL-1(+) patients 60 or younger, the top Lp(a) quartile had about 9 times the odds of coronary disease compared with the bottom quartile.

That study also found that IL-1(+) patients above the median for oxidized phospholipids came to the catheterization lab about 3.9 years earlier and had worse four-year survival free of cardiovascular events. This is a signal, not a treatment rule. The study was observational and done in people already sick enough to need angiography. An independent replication in 603 non-diabetic angiography patients from Ioannina found the same pattern: IL-1(+) genotypes modulated Lp(a)-associated coronary risk and events, again strongest in patients 60 or younger.

The useful part is the interaction. Oxidized phospholipids are inflammatory fats carried mainly on Lp(a) and other ApoB particles. If you are under 60, have high Lp(a) or high ApoB, and carry an IL-1 positive result, the result argues against waiting for a population risk calculator to catch up.

Reconciling the Mixed Verdict

The IL-1 genotype does not tell you whether you will get a disease. It tells you about one inflammatory pathway. Whether that turns into gum loss, early coronary disease, or nothing obvious depends on smoking, plaque bacteria, ApoB, Lp(a), blood pressure, diabetes, and treatment. A positive result without those exposures often adds little. A positive result on top of them can matter.

How to Read Your Own Result

An IL-1 positive result is not a diagnosis. It should raise the priority of things you can verify: a periodontal exam with probing depths and bone-level review, a direct check of ApoB and Lp(a), and hs-CRP if you want a current inflammation signal.

If your gums bleed, if you smoke, or if a parent lost teeth early, a positive result supports shorter dental recall intervals and lower tolerance for ongoing gingivitis. If ApoB or Lp(a) is high, it supports earlier attention to lipid lowering. The genotype does not tell you which drug to take.

A negative result does not clear your gums or arteries. Most gum disease and most heart disease happens in people without this specific pattern. The genotype is a modifier, not the whole answer.

One-Time Test, Lifetime Use

There is nothing to trend in the genotype. A single clean saliva or cheek sample is usually enough. What needs follow-up is downstream risk: pocket depths and bone levels at dental visits, ApoB during lipid follow-up, hs-CRP when you are checking inflammatory risk, and Lp(a) at least once if you have not measured it already. Lp(a) usually does not need yearly repeat testing unless a result is borderline, a secondary cause is suspected, or you are tracking a treatment that can change it.

When the Result Can Mislead You

A genetic result can still mislead if you treat the report as bigger than it is.

• Panel coverage: the test looks at specific IL1A and IL1B variants. Rare variants elsewhere in the IL-1 pathway will not show up. A negative result rules out only what was tested.
• Ancestry: the classic composite was defined mainly in white and European-heritage populations. Variant frequencies and risk estimates can differ by ancestry, with much lower carrier rates reported in Asian cohorts.
• Genotype definition: some periodontal studies use the two-variant composite. The cardiovascular catheterization study used a broader three-variant IL-1(+) grouping. Do not treat those as interchangeable.
• Uncertain variants: a targeted IL-1 composite usually reports known variants as positive or negative. Broader sequencing may find a DNA change the lab cannot yet classify. That is not the same as being IL-1 positive.
• Inherited versus acquired DNA changes: this test is meant to read DNA you were born with. A blood cancer, tumor sequencing report, or prior stem-cell transplant can confuse the source if the lab uses the wrong sample type.
• Sample quality: food does not change DNA, but a saliva sample with too little cheek-cell DNA or another person's DNA may fail quality control.
• Clinical versus consumer assays: a direct-to-consumer report may cover overlapping SNPs, but it is not the same as a clinical IL-1 composite result when a dental or cardiovascular decision depends on it.

What to Do With a Positive Result

There are no drugs that undo the genotype. The decision pathway is about where to look next. First, make sure the variant definition on your report matches the evidence you are using. If the result conflicts with a prior DNA report, or if a major medical decision depends on it, confirm it with a second clinical assay.

On the dental side, get a full periodontal chart and bone-level review. If there is pocketing, bleeding, or prior bone loss, cleanings every 3 or 4 months are more defensible than waiting six months. Smoking is the exposure that most clearly stacks with this genotype.

On the cardiovascular side, check ApoB, Lp(a), and hs-CRP. If ApoB or blood pressure is high, do not wait for age alone to make the risk obvious. A preventive cardiologist or lipidologist is useful if you are under 60 with high ApoB, high Lp(a), early plaque, or a strong family history.

Share the result with adult first-degree relatives. Because this is inherited, parents, siblings, and children are more likely than average to carry the same pattern. The exact odds depend on which variants each parent carries. If early tooth loss or early heart disease runs in the family, their own testing and downstream checks may matter.