A study conducted by Wohlfahrt et al. [47] also revealed no association between IL6 c.-174G>C polymorphism and other polymorphisms in CTLA-4 DEFB1, ICAM-1, FasL, ICOS, CCR5, OPG, and OPN genes in subjects with periodontal disease from USA. The gene discussed is CCR5; the disease is periodontal disorder.