TLR4 and periodontitis: In a study on HIV-positive North American patients with periodontitis, 8 SNPs in 6 TLR genes (TLR1 (n = 2), TLR2 (n = 1), TLR4 (n = 1), TLR6 (n = 1), TLR8 (n = 2), and TLR9 (n = 1)) were positively associated with P. gingivalis (2 SNPs), T. denticola (6 SNPs), and T. forsythia (1 SNP) [19].