[Association between matrilin-1 gene polymorphism and bracing effectiveness in adolescent idiopathic scoliosis girls].

OBJECTIVES

To investigate the association between matrilin-1 gene polymorphism and bracing effectiveness in adolescent idiopathic scoliosis girls.

METHODS

In a prospective study, AIS girls treated with standard bracing from January 2005 to December 2008 were included and followed up. All subjects of the study met the following criteria: female; skeletally immature (Risser sign grade 0 - 3); before menarche or < 1.5 years after menarche; Cobb angle 20 degrees - 40 degrees ; scoliosis caused by congenital, neuromuscular and other cause were excluded; no evidence of bone diseases, metabolic diseases or other condition known to affect bone metabolism; no history of bracing before onset; follow-up with an interval of 3 months, and total follow-up time > 2 years. Subjects met one of the following conditions was excluded: the final follow-up time < 2 years; bad compliance (ratio of the actual daily wearing time to proposed wearing time) of bracing (< 75%); change of bracing without doctor's order. Cobb angle of major curve was recorded before the bracing initiation and at the final follow-up. A progression of 6 degrees or more was considered to be a failure of bracing. The rs1149048 polymorphism in promoter of matrilin-1 gene was chosen for genotyping by PCR-RFLP method. Differences in age at initial visit, Risser sign, Cobb angle and genotype distribution were compared between brace failure and brace success groups.

RESULTS

Seventy seven patients with AIS were included, with a mean age at (13.0 +/- 1.5) years and a mean Cobb angle at (30.3 +/- 11.9) degrees . After an average duration of 2.6 years follow-up, mean Cobb angle was 30.3 degrees +/- 11.9 degrees . There were 19 cases (24.7%) in bracing failure and 58 cases (75.3%) in bracing success. The initial Cobb angle was larger in bracing failure group compared with bracing success group (P > 0.05). Patients with double major curve were found to have the lowest bracing failure rate (19.4%), but there was no significant difference compared with other curve patterns. Bracing failure rate was marked higher in individual with genotype GG (66.7%) than that with genotype AA or AG.

CONCLUSIONS

Progression of most mild or moderate AIS can be managed by early standardized bracing treatment. It is shown that large initial Cobb angle and genotype GG of matrilin-1 gene are indicative of less bracing effectiveness.