TLR2, the toll-like receptor 2 gene, encodes a cell surface receptor that is one component of the innate immune system. TLR2 appears to be involved in helping to activate various cytokines, such as interleukin 12 IL12B, as the mobilizes to defend itself against microbial and viral invaders such as the Lyme disease bacterium or herpes viruses. Variations in human TLR2 gene sequences may therefore be associated with variations in the way individuals respond to infections.
TLR2 SNPs that have been reported include:
- rs5743708, known as R753Q, is potentially somewhat protective against Lyme disease. [PMID 16081826] Among patients with inflammatory bowel disease, R753Q increases the odds of pancolitis ~5 fold (OR 4.7, RR 3.3 for R753Q heterozygotes). [PMID 16374251] Having a functional, wild-type TLR2 rather than R753Q appears to minimize the chances of developing restenosis following a percutaneous transluminal coronary angioplasty (PTCA). [PMID 15875151]
- rs1898830, known as -15607A/G, is associated with shedding and lesion frequency of genital herpes simplex virus type 2 HSV-2 outbreaks. [PMID 17624834]
- rs3804099, known as T597C, is associated with a 3-6 fold higher risk of meningitis of tubercular origin. [PMID 17554342]
- rs3804100, known as 1350T/C, was studied in conjunction with rs3804099. By itself, there was a weak protective effect by the homozygous (C;C) rs3804100 genotype; but when combined in the rs3804099(T)-rs3804100(C) haplotype (known as the "TLR2-Ht4" haplotype) a strong protective effect was reported, with an odds ratio of 90, against developing Type-1 diabetes in one Korean population studied. Basically, in 381 diabetes patients studied, 0 carried even one Ht-4 haplotype, while 100 out of 947 control (non-diabetic) individuals carried either one or two Ht-4 haplotypes. [PMID 15699513]
- No associations were found in an Italian population between TLR2 Arg677Trp or Arg753Gln and myocardial infarction. [PMID 18442320]