Study Design. Case-control study.
Objective. This study is to replicate the association between the promoter polymorphisms of matrix metalloproteinase (MMP)-3 (−1171 5A/6A rs3025058) and interleukin (IL)-6 genes (−174G/C rs1800795) and adolescent idiopathic scoliosis (AIS) in a Chinese Han population.
Summary of Background Data. Recently, promoter polymorphisms in MMP-3 and IL-6 have been reported to be associated with AIS. Such genetic association, if confirmed by replication in other samples, would point to a primary degenerative defect in the disc or nucleus pulposus and inflammation as the key pathogenic mechanisms of AIS.
Methods. A total of 487 Chinese girls with AIS and 494 healthy age-matched adolescent girls were recruited consecutively during a 3-year period. The same genotyping technique as the original report was used to detect promoter polymorphisms of the MMP-3 and IL-6 genes. Statistical analysis of genotype frequencies between AIS patients and normal controls were performed by χ2 test.
Results. In this association study of the MMP-3 polymorphism and the risk of scoliosis, no significant difference was found between cases and controls, both in term of allelic association (6A: 81.2% in cases vs. 81.8% in controls, 5A: 18.8% in cases vs. 18.2% in controls, P = 0.745) or genotype association (6A/6A: 65.9% in cases vs. 66.2% in controls, 5A/6A: 30.6% in cases vs. 31.2% in controls, and 5A/5A: 3.5% in cases vs. 2.6% in controls; P = 0.733). Among AIS patients, the maximal Cobb angles were also not different among MMP-3 genotypes (6A/6A: 31.1° ± 9.7°, 5A/6A: 29.1° ± 10.5°, and 5A/5A: 29.4° ± 11.2°; P = 0.392). As for IL-6 polymorphism, −174G/C polymorphism was not found in the Chinese AIS patients, and all 100 AIS patients and 100 normal controls were found to carry the G/G wild type.
Conclusion. This study did not find any significant association of promoter polymorphisms of the MMP-3 (−1171 5A/6A rs3025058) and IL-6 gene (−174G/C rs1800795) with AIS. The results indicate that the MMP-3 promoter polymorphism is not associated with AIS in the Chinese population. Further studies, however, are needed to rule out the potential association with other promoter polymorphisms in IL-6.