Genetic polymorphism of Clara cell secretory protein 16KDa (CC16) and susceptibility to asthma, a meta-analysis

Clara cell secretory protein 16KDa (CC16) is the major secretory protein of the Clara cells. The gene encoding CC16 has been implicated as potential susceptibility gene for asthma. Published studies between genetic polymorphism of CC16 at position 38 and asthma risk are controversial. Most of these studies are based on small sample size. To clarify the role of the A38G CC16 polymorphism on the risk of developing asthma, we carried out a meta-analysis of the research published between January 1988 and August 2005. In the present study, 11 case-control studies with 2362 subjects (1262 controls and 1100 patients) were eligible for meta-analysis. The fixed-effects method was used when there was no significant heterogeneity between the results of the individual studies being pooled, whereas, the random-effects method was used when there was heterogeneity between the studies. The overall ORs of the asthma risk were not associated with the CC16 genotypes (For AG vs GG: OR=1.09, 95% CI: 0.90-1.32; For AA vs GG: OR=1.05, 95% CI: 0.79-1.39; For AG+AA vs GG: OR=1.09, 95% CI: 0.91-1.30). It should be noted that similar results were obtained when we used the stratified data, adjusted for age and smoking status of the subjects. In conclusion, the CC16 A38G polymorphism was not associated with asthma risk in the present meta-analysis