Your Body's Attacking Itself. Here's the Genetic Reason.

HLA genes are the bouncers at your immune system’s door. They decide which foreign proteins and your own proteins get shown to your T cells, the cells that decide whether to attack. HLA-DQ2 is one of the most important variants controlling this presentation. If your immune system can’t see a threat properly, it misclassifies your own proteins as foreign.

Approximately 25-30% of people with European ancestry carry HLA-DQ2. People with this variant have a dramatically increased risk of celiac disease, type 1 diabetes, and other autoimmune conditions because their immune system is primed to see certain patterns as threats. The variant itself doesn’t cause autoimmune disease on its own, but it loads the gun. Environmental factors like viral infections or intestinal damage pull the trigger.

You might notice that certain foods trigger inflammation, or that your symptoms flare after you’ve been sick. This is HLA-DQ2 doing its job: presenting antigens in a way that makes your immune system hypervigilant. Your immune system isn’t broken; it’s just been given the wrong instruction manual.

CTLA4 is the brake pedal on your T cells. When functioning normally, CTLA4 tells activated T cells to stop dividing and attacking. It’s the most important off-switch your immune system has. If CTLA4 isn’t working properly, your T cells keep multiplying and attacking even when they should have stopped.

The CTLA4 +49A>G variant is carried by roughly 45% of the population. People with the G allele have reduced CTLA4 function, meaning their T cells stay active longer and divide more aggressively. This is especially dangerous in autoimmune conditions because it means your immune attack, once started, is harder to stop.

You might find that once your autoimmune symptoms start, they seem to spiral; flare-ups take weeks to calm down even after the trigger is gone. This is CTLA4 struggling to apply the brakes. Your immune system is like a car with a faulty brake system. It accelerates just fine, but stopping takes much longer than it should.

TNF, or tumor necrosis factor-alpha, is your immune system’s megaphone. It broadcasts inflammatory signals throughout your body. TNF is useful when you’re fighting an infection, but if it stays elevated, it drives chronic inflammation and tells your immune system to keep attacking.

The TNF -308G>A variant is carried by roughly 30% of people with European ancestry. The A allele causes your cells to produce significantly more TNF-alpha, amplifying inflammatory signals across your entire body. This means that when your immune system decides to attack, the attack is louder, longer, and harder to control.

You might notice that your inflammatory markers stay elevated even when your symptoms improve, or that you experience widespread pain and fatigue alongside your autoimmune condition. This is TNF keeping the inflammatory fire burning. Even when the initial trigger is gone, TNF keeps broadcasting the attack signal.

IL6, interleukin-6, is the second megaphone in your immune system’s toolkit. While TNF broadcasts the initial alarm, IL6 sustains the inflammatory response and keeps immune cells activated and multiplying. Elevated IL6 also drives neuroinflammation, which is why autoimmune disease so often comes with brain fog and mood changes.

The IL6 -174G>C variant is present in roughly 40% of the population. The C allele increases IL-6 production, extending and amplifying the inflammatory cascade. This means that once inflammation starts, it persists longer and spreads more broadly through your body.

You might experience brain fog, depression, or anxiety alongside your physical autoimmune symptoms. This is IL6 crossing the blood-brain barrier and triggering neuroinflammation. Your immune attack isn’t just happening in your joints or skin; it’s happening in your brain too, affecting mood and cognition.

PTPN22 is one of your immune system’s most important regulators. It acts like a phosphatase, a protein that removes signals from immune cells, essentially telling them to calm down. If PTPN22 isn’t working properly, immune cells stay activated longer and are more likely to attack self-tissues.

The PTPN22 R620W variant (rs2476601) is particularly important in autoimmune disease. People carrying the W allele have impaired PTPN22 function, meaning their immune cells receive fewer off-signals and remain activated longer. This variant has been found in many autoimmune conditions, including rheumatoid arthritis, lupus, and type 1 diabetes.

You might notice that your immune system overreacts to minor infections or triggers, or that once your autoimmune condition starts, it keeps progressing. This is PTPN22 failing to apply the off-switch. Your immune cells are like security guards who forgot how to stand down after catching a trespasser.

IRF5, interferon regulatory factor 5, is a master switch in your immune system. It decides whether your immune cells activate a type I interferon response, which is appropriate for fighting viruses, or whether they activate inflammatory pathways. When IRF5 function is dysregulated, your immune system chooses the inflammatory path even when it shouldn’t.

IRF5 variants are particularly important in lupus and other systemic autoimmune conditions. People with IRF5 variants have increased activation of inflammatory gene programs, meaning their immune system is primed to choose attack mode over tolerance. This creates a state of immune hypervigilance where your system is constantly ready to assault.

You might experience photosensitivity, malar rash, or systemic symptoms that flare unpredictably. This is IRF5 keeping your immune system in attack mode. Even minor triggers that shouldn’t activate your immune system do, because IRF5 has tilted the balance toward inflammation.