Polymorphisms in promoter regions of MMP-3 and IL-6 genes are not associated to adolescent idiopathic scoliosis (AIS) gender bias

Abstract

Study design: A retrospective study in Chinese Han people.

Purpose: To explore whether promoter polymorphisms of matrix metalloproteinases-3 (MMP-3) (rs3025058) and interleukin-6(IL-6) (rs1800795) genes are associated to AIS gender bias.

Methods: A total of 200 patients (100 boys and 100 girls) with AIS and 200 healthy age-matched adolescents were recruited from July 2008 to August 2013 in our scoliosis center. All AIS patients had Cobb angles larger than 20°, average 43 ± 3.6° (range 24-72°). A case-control study using genotypic technique was conducted to explore whether promoter polymorphisms of MMP-3 and IL-6 were associated to AIS gender bias. In addition, to confirm the association between gene variants of MMP-3 and IL-6 and AIS. Statistical analysis of genotype frequencies between AIS patients and normal controls was performed by X^2 test.

Results: The frequency of 5A/5A genotype of MMP-3 gene in patients with AIS was higher than in controls (19% versus 9.5% p= 0.007), in the sub-divided groups depend on gender, no significant difference was found between AIS girls and boys in the frequency of 5A/5A genotype of MMP-3 (20% in girls versus 18% in boys p= 0.718). No significant difference was found between AIS and controls in the frequency of G/G genotype of IL-6 (97.5% versus 98%). In the sub-divided groups depend on gender, no significant difference was found between AIS girls and boys in the frequency of G/G genotype of the IL-6 gene (98% in girls versus 97% for boys).

Conclusions: The promoter polymorphism of the MMP-3 gene was confirmed to have an association with AIS and the promoter polymorphism of the IL-6 gene was lack of association with AIS. Besides, both gene variants of MMP-3 and IL-6 were not associated to AIS gender bias.

Keywords: Adolescent idiopathic scoliosis; gender; interleukin-6; matrix metalloproteinases-3.