[A meta-analysis on interleukin-1 gene cluster polymorphism and genetic susceptibility for ankylosing spondylitis].

OBJECTIVE

To investigate the association between interleukin (IL)-1 gene cluster polymorphism and the genetic susceptibility for ankylosing spondylitis (AS).

METHODS

Relevant published data were retrieved through Pubmed, EMBASE, Cochrane library and Chinese Bio-medicine Database (CBM). Studies eligible for this meta-analysis had to meet all the following inclusion criteria: (1) the content was associated with population-based case-control studies, (2) the study was on the relationship between the IL-1 gene cluster polymorphism and AS, (3) the diagnosis of AS was based on the modified New York criteria (1984) by the rheumatologist. (4) the raw data including the frequencies of alleles and certain genotypes in case and control groups could be collected. and (5) the distribution of studied loci in the populations was in accord with the Hardy-Weinberg equilibrium. Researches that didn't meet the inclusion criteria, as well as the duplicated reports, family-based studies were excluded. All analyses were conducted with the software 'Review Manager' Version 4.2.8.

RESULTS

(1) A total of 6 literatures, including 9 population samples, were studied. The overall combined data were verified to be heterogeneous, and the heterogeneity disappeared after stratification by the race. Then, the fixed-effect model could be applied. (2) The combined data revealed the frequencies of allele 2 and its genotypes of IL-1RN intron 2 variable number of tendem repeats were higher in the AS groups than in the controls in the Caucasian population (allele 2: OR=1.52, 95% CI=1.26 approximately 1.84, P<0.01; genotype: OR=1.33, 95% CI=1.04 approximately 1.70, P<0.05), but lower in the AS groups than in the controls in the Mongolian population (allele 2: OR=0.55, 95% CI=0.38 approximately 0.81, P<0.01; genotype: OR=0.51, 95% CI=0.34 approximately 0.77, P<0.01). (3) The minor allele T of IL-1A -889C>T (rs1800587) was higher in the AS group than in the controls in the Caucasian population (allele T: OR=1.36, 95% CI=1.12 approximately 1.66, P<0.01; genotype C/T+T/T: OR=1.56, 95% CI=1.20 approximately 2.03, P<0.01). This distribution could not be found in the Mongolian population for this SNP. (4) The minor allele G of IL-1F8 SNP (rs1900287) was higher in the AS group than in the controls in the Caucasian population (OR=1.22, 95% CI=1.04 approximately 1.44, P<0.05).

CONCLUSION

The genetic susceptibility for AS may be associated with the IL-1 gene cluster polymorphism. The relevant polymorphic sites include IL-1RN 86bp VNTR in intron 2, IL-1A -889C>T (rs1800587) and IL-1F8 SNP (rs1900287). Furthermore, there is a distinct discrepancy for this association among races.