TYK2 rs34536443: Understanding the P1104A Autoimmune Variant
The rs34536443 variant is a specific genetic change in the TYK2 gene that results in a protein alteration known as P1104A. Research indicates that individuals carrying this variant may have a reduced risk of developing certain autoimmune diseases, such as rheumatoid arthritis and psoriasis.
What each genotype means
Typical TYK2 activity
This is the most common genotype, representing the standard version of the TYK2 gene. Individuals with this genotype do not carry the P1104A protective variant associated with reduced autoimmune risk.
This is the major genotype found in the vast majority of the global population.
Reduced TYK2 activity carrier
You carry one copy of the P1104A variant, which is associated with a reduced risk of certain autoimmune conditions like psoriasis and rheumatoid arthritis. Research suggests this variant may slightly dampen immune signaling, though the clinical impact for a single copy is generally less pronounced than in those with two copies.
Carried by a small percentage of the population, with frequencies varying by ancestry.
Protective TYK2 variant
You carry two copies of the P1104A variant, which is linked to a reduced risk of developing several autoimmune diseases. However, this variant is also associated with a significantly increased risk of developing tuberculosis if exposed to the bacteria, as it may impair certain immune responses; please discuss any specific health concerns with your clinician.
This genotype is rare, occurring in approximately 1 in 600 people of European ancestry and even less frequently in other global populations.
What is rs34536443?
The variant rs34536443 is a single nucleotide polymorphism (SNP) located within the TYK2 gene. In genetic terms, this specific change causes a missense mutation, meaning it results in the substitution of one amino acid for another in the resulting protein. Specifically, the proline at position 1104 is replaced by an alanine, which is why the variant is frequently referred to in scientific literature as P1104A. This change is located in a region of the gene that is critical for the protein's function. Because this variant alters the structure of the TYK2 protein, it has been the subject of extensive study to understand how it influences the body's immune response and susceptibility to various inflammatory conditions.
The Role of the TYK2 Gene
The TYK2 gene provides instructions for making a protein called tyrosine kinase 2. This protein belongs to a family of enzymes known as Janus kinases, which are essential for signaling pathways that allow cells to communicate with one another. TYK2 is particularly important for the immune system, as it helps transmit signals from cytokines—small proteins that regulate immune cell activity—into the cell. When these signaling pathways are active, they trigger various immune responses. Because TYK2 is a key component in these pathways, variations in the gene can lead to differences in how the immune system reacts to stimuli. When the TYK2 protein is less active, as is the case with the P1104A variant, it can dampen certain inflammatory signals, which is why it is studied for its potential protective effects against overactive immune responses.
Research and Autoimmune Associations
Scientific research has consistently identified rs34536443 as a protective factor against several autoimmune diseases. Genome-wide association studies have linked this variant to a lower risk of conditions such as rheumatoid arthritis, systemic lupus erythematosus, and psoriasis. The mechanism behind this protection is thought to be the variant's role as a 'hypomorph,' meaning it results in a protein with reduced, but not entirely absent, function. By modulating the signaling of cytokines like interferon, the variant may prevent the immune system from becoming overactive. While the evidence for these associations is strong in the context of autoimmune susceptibility, it is important to note that this is a complex trait influenced by many genetic and environmental factors. The variant does not guarantee immunity from these conditions, but rather statistically correlates with a lower likelihood of their development.
Population Frequency
The frequency of the rs34536443 variant varies significantly depending on an individual's ancestral background. In European populations, the minor allele frequency is approximately 5%. This means that a small but notable portion of the population carries at least one copy of this variant. Because the frequency is relatively low, it is not considered a common variant in all global populations, and its prevalence can differ markedly in non-European groups. Understanding these frequency differences is a key part of genetic research, as it helps scientists determine how genetic traits are distributed across the globe and how they might contribute to health disparities or shared disease risks among different ancestral groups.
Interpreting Your Genetic Information
If you have access to your genetic data and find that you carry the rs34536443 variant, it is important to view this information in the proper context. Genetic associations are statistical observations made across large groups of people and cannot predict an individual's health outcome with certainty. Many factors, including lifestyle, environment, and other genetic markers, play a significant role in the development of autoimmune diseases. This information should not be used to diagnose any condition or to make decisions about medical treatments. If you have concerns about your health or your risk for autoimmune conditions, the best course of action is to consult with a qualified healthcare professional or a genetic counselor. They can help you interpret your results in the context of your personal and family medical history.
How common is this variant?
The minor allele frequency for rs34536443 is approximately 5% in European populations, though this frequency varies across different global ancestries.
Frequently asked questions
Does having the rs34536443 variant mean I will never get an autoimmune disease?
No. Genetic variants only provide a statistical change in risk. Many other factors, including your environment and other genes, contribute to the development of autoimmune diseases.
Can I use this information to change my medication?
Absolutely not. You should never change or stop any medication based on genetic test results without first consulting your doctor or pharmacist.
Is rs34536443 the same as the TYK2 inhibitor drugs?
The variant is a natural genetic difference that reduces TYK2 function. TYK2 inhibitor drugs are medications designed to achieve a similar effect by blocking the protein's activity to treat autoimmune conditions.
Where can I find more information about my specific genetic results?
You should speak with a board-certified genetic counselor or your primary care physician. They can help you understand your results in the context of your overall health.
Sources & further reading
Educational information only, last refreshed 10/14/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant in the TYK2 gene is identified as a shared causal signal in the genetic architecture of psoriasis and rheumatoid arthritis.
This TYK2 variant shows evidence of antagonistic pleiotropy, with opposite effects on the risk of psoriasis versus rheumatoid arthritis.
This variant in the TYK2 gene provides protection against some autoimmune diseases but is linked to a higher risk of severe COVID-19 complications.