Background and objective: Genetic susceptibility for development of chronic obstructive pulmonary disease (COPD) is under intensive investigation. Among the three alleles of vitamin D binding protein, or group-specific (GC) components, some have suggested that having GC-1F and GC-2 alleles was associated with a risk of COPD. Although previous studies have shown considerable variance, no meta-analysis has been conducted.
Methods: Through four databases, two independent investigators searched for case-control studies providing sufficient data to calculate odds ratios by the vitamin D binding protein allele variant and genotype variant for a case of COPD. Studies whose control did not satisfy the Hardy-Weinberg equilibrium (Chi-square P ≥ 0.05) were excluded. We used a fixed-model to estimate the pooled odds ratio at both allele and genotype level.
Results: Of 141 candidate studies, six were included. We analysed 1712 subjects, consisting of 466 Asians, 1246 Caucasians, 531 COPD cases and 1181 non-COPD controls. The prevalence of each allele among the 1181 controls was as follows: GC-1F 14.0%, GC-1S 53.8% and GC-2 31.9%. When compared to GC-1S, the GC-1F allele and GC-2 allele were associated with COPD risk with pooled odds ratios of 1.44 (95% CI 1.14-1.83, P = 0.002) and 0.83 (95% CI 0.69-0.996, P = 0.045), respectively. When compared to the 1S-1S genotype, the 1F-1F genotype was a risk factor of COPD with pooled odds ratio of 2.64 (95% CI 1.29-5.39, P = 0.008).
Conclusion: The GC-1F allele of the vitamin D binding protein was a risk for COPD in recessive mode.
Keywords: Mendelian model; allele; group-specific component; inheritance; single nucleotide polymorphism.
© 2014 Asian Pacific Society of Respirology.