The Chemokine Receptor 5 Delta32 Polymorphism and Type 1 Diabetes, Behcet’s Disease, and Asthma: A Meta-analysis

OBJECTIVE: The aim of this study was to determine whether the functional chemokine receptor 5 delta32 (CCR5-Δ32) polymorphism is associated with susceptibility to type 1 diabetes (T1D), Behcet's disease (BD), and asthma. RESULTS: Fourteen studies encompassing 9,656 cases and 12,431 controls, including 6 on T1D, 5 on BD, and 3 on asthma, were available for meta-analysis. The meta-analysis showed a significant negative association between T1D and the CCR5-Δ32 allele (odds ratio [OR] = 0.854, 95% confidence interval [CI] = 0.800-0.912, p = 2.2 × 10⁻⁷). Stratification by ethnicity and analysis of the Δ32Δ32 + Δ32W genotype indicated a significant negative association between the CCR5-Δ32 allele and T1D in Europeans (OR = 0.857, 95% CI = 0.802-0.915, p = 3.5 × 10⁻⁸; OR = 0.896, 95% CI = 0.808-0.932, p = 9.3 × 10⁻⁶, respectively). The meta-analysis showed a positive association between BD and the Δ32Δ32 + Δ32W genotype (OR = 1.403, 95% CI = 1.008-1.954, p = 0.045). Stratification by HLA-B51 status indicated an association between the CCR5-Δ32 allele and HLA-B51-positive BD, but not HLA-B51-negative BD (OR = 1.619, 95% CI = 1.070-2.451, p = 0.023; OR = 1.036, 95% CI = 0.674-1.593, p = 0.872, respectively). No association was found between the CCR5-Δ32 polymorphism and asthma. CONCLUSIONS: This meta-analysis demonstrates that the CCR5-Δ32 polymorphism acts as a protective factor in T1D development in Europeans, and a risk factor for BD among HLA-B51 carriers. However, no association was found between the CCR5-Δ32 polymorphism and asthma.