TLR1 rs5743618: What Your Genotype Means
TLR1 rs5743618 is a well-studied missense variant in the Toll-like receptor 1 gene, causing an isoleucine-to-serine amino acid swap (I602S). This variation alters receptor trafficking to the cell surface, dampening innate signaling pathways. Research primarily associates it with altered susceptibility to mycobacterial infections like tuberculosis and leprosy, as well as downstream differences in allergic response patterns.
What each genotype means
Typical TLR1 surface expression
This genotype represents the ancestral form of the TLR1 protein, often referred to as 602I. Research indicates that individuals with this genotype typically exhibit normal levels of TLR1 receptor trafficking to the cell surface, supporting standard innate immune recognition of bacterial lipopeptides.
This is the major genotype in many populations, though frequencies vary significantly by ancestry, being more common in African populations and less common in European populations.
Intermediate TLR1 surface expression
This heterozygous genotype results in a mix of standard and altered TLR1 protein, often referred to as the I602S variant. Studies suggest that carriers may show intermediate levels of TLR1 surface expression and immune response compared to those with the AA genotype.
This genotype is frequently observed in European populations, where the G allele is common.
Reduced TLR1 surface expression
This genotype, often referred to as 602S, is associated with reduced trafficking of the TLR1 receptor to the cell surface. Some research suggests this may lead to a dampened immune response to certain bacterial pathogens, with some studies observing an association with increased susceptibility to tuberculosis in specific pediatric populations; however, these findings are not consistent across all ethnic groups and further research is required.
Carried by a significant portion of individuals of European ancestry, while being much less common in East Asian populations.
What is the TLR1 rs5743618 Variant?
The single nucleotide polymorphism rs5743618 represents a point mutation located in the Toll-like Receptor 1 (TLR1) gene on chromosome 4. At the molecular level, this substitution involves a thymine-to-guanine change (historically noted as T1805G or I602S), which changes an isoleucine into a serine at codon position 602 of the protein. The I602S alteration occurs in the transmembrane region of the receptor and directly impacts its ability to traffic to the cell surface. Because the TLR1 protein must reach the cell surface to pair with TLR2 and recognize microbial ligands, the altered trafficking caused by the variant allele reduces baseline signaling and functional cell-surface expression.
Biological Function of the TLR1 Gene
TLR1 encodes an essential pattern recognition receptor within the innate immune system. Working as a heterodimer alongside TLR2, TLR1 detects triacylated lipopeptides found in bacterial cell walls, including those of mycobacteria and Borrelia species. When functioning normally, activation of this receptor cascade stimulates an innate inflammatory burst and promotes Th1-skewed adaptive immune responses. By modulating how efficiently TLR1 reaches the membrane, the rs5743618 polymorphism effectively tunes the gain of this initial alarm system, dampening downstream inflammatory signaling and altering the cytokine milieu.
Associated Traits and Research Evidence
Research evaluating rs5743618 spans infectious and immune-mediated conditions. The altered signaling seen with the serine (G) variant has been linked to differing susceptibility patterns for mycobacterial diseases such as leprosy and tuberculosis, as well as altered immune responses in Lyme disease. In pediatric cohorts, studies have also associated rs5743618 genotypes with allergic phenotypes, including atopic eczema, asthma, and allergic rhinitis, likely due to diminished Th1 responses skewing the immune balance. However, overall evidence across diverse populations remains limited and sometimes mixed, with effect sizes varying significantly between cohorts and ancestries.
How to Interpret Your Results
Carrying one or more copies of an altered allele at rs5743618 is not a diagnosis of an immune disorder or a guarantee of illness. Instead, it reflects a modest statistical shift in cellular responsiveness within scientific research studies. The human immune system relies on extensive functional redundancy across dozens of receptors and pathways. Personal disease risk depends primarily on environmental exposures, lifestyle factors, and thousands of other genetic variants. This result should not be used to self-diagnose immune vulnerabilities or alter clinical treatments.
How common is this variant?
The minor allele frequency (MAF) of rs5743618 varies substantially across global populations, reaching approximately 0.25 in European ancestries while remaining rare at around 0.01 in East Asian populations.
Frequently asked questions
Does having the rs5743618 variant mean I have an immune deficiency?
No. The rs5743618 variant is a common genetic variation, not a primary immunodeficiency. While it subtly influences receptor trafficking at the cellular level, the immune system has multiple redundant mechanisms to detect and fight infections.
Can rs5743618 determine whether I will get asthma or allergies?
No, it cannot diagnose or predict asthma or allergies. While researchers have noted statistical associations between this variant and atopic conditions in certain populations, allergic diseases are complex and heavily influenced by environmental triggers and multiple genes.
What does the I602S notation mean?
I602S refers to the change in the TLR1 protein sequence caused by this SNP. At amino acid position 602, an isoleucine (I) is replaced by a serine (S), which disrupts how the receptor is transported to the outer cell membrane.
Can I modify my diet or take supplements to alter my TLR1 function?
There are no scientifically proven dietary supplements, medications, or lifestyle changes designed to counteract or target the rs5743618 variant. Healthy lifestyle practices that support overall immune health remain the standard recommendation.
Sources & further reading
Educational information only, last refreshed 9/12/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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