**4.1 CCR1 and CCR3**

C–C chemokine receptor type 1 (CCR1) and C–C chemokine receptor type 3 (CCR3) encode the chemokine receptor belonging to the G protein-coupled receptor super family. These receptors play an important role in the accumulation and activation of inflammatory cells [73, 74]. The rs7616215 SNP located in the CCR1-CCR3 locus was showed to be associated with BD in a Turkish population [25]. The CCR1 gene was associated to susceptibility with BD in multiple cohorts including Turkish, Japanese, and Iranian cohorts [23, 25]. Hou et al. reported that the CCR1-CCR3 (rs13084057 in the 30 UTR of CCR1; rs13075270 and rs13092160 in the intergenic region between CCR1 and CCR3) polymorphisms also associated with BD in a Chinese population [75].
