PURPOSE: To investigate whether the predisposition genes previously reported to 
be associated with the occurrence or curve severity of adolescent idiopathic 
scoliosis (AIS) play a role in the effectiveness of brace treatment.
METHOD: A total of 312 AIS patients treated with bracing were enrolled in this 
study. The Cobb angle of the main curve was recorded at the beginning of brace 
treatment as well as at each follow-up. The patients were divided into two 
groups according to the outcome of brace treatment (success/failure). The 
failure of brace treatment was defined as a curve progression of more than 5° 
compared to the initial Cobb angle or surgical intervention because of curve 
progression. Single nucleotide polymorphism (SNP) sites in the genes for 
estrogen receptor α (ERα), estrogen receptor β (ERβ), tryptophan hydroxylase 1 
(TPH-1), melatonin receptor 1B (MTNR1B) and matrillin-1 (MATN1), which were 
previously identified to be predisposition genes for AIS, were selected for 
genotyping by the PCR-RFLP method. Differences of genotype and allele 
distribution between the two groups were compared by the χ(2) test. A logistic 
regression analysis was used to figure out the independent predictors of the 
outcome of brace treatment.
RESULTS: There were 90 cases (28.8%) in the failure group and 222 cases (71.2%) 
in the success group. Patients in the failure group were associated with the 
genotype GA (50.9 vs. 17.9% p < 0.001) and the G allele (27.1 vs. 12.0%, p < 
0.001) at SNP rs9340799 of the ERα gene. Similarly, they were also associated 
with the genotype AT (33.3 vs. 13.0%, p = 0.002) and the A allele (16.7 vs. 
9.6%, p = 0.033) at SNP rs10488682 of the TPH-1 gene. For MTNR1B, the difference 
of genotype distribution between the two groups was found to be statistically 
significant, while the difference of allele distribution between the two groups 
was found to be marginally statistically significant; for the MATN1 and ERβ 
genes, we found no significant differences of the genotype or allele 
distribution between the two groups. In the logistic regression analysis, ERα 
and TPH-1 were demonstrated to be independent factors predictive of bracing 
effectiveness.
CONCLUSIONS: ERα and TPH-1 might be potential genetic markers that could predict 
the outcome of brace treatment. Patients with the G allele at the rs9340799 site 
of the ERα gene and the A allele at the rs10488682 site of the TPH-1 gene are 
prone to be resistant to brace treatment.