Finally, another recent gene-environment interaction study investigated the possible effect of interactions between serologically documented exposure to T. gondii, CMV, HSV-1 or HSV-2 and polymorphisms of TLR2, TLR4 and NOD2 genes, which encode for pivotal pattern-recognition receptors, in a sample of 138 BD patients [130]. Here, TLR4 is linked to Behcet disease.