LBX1, ESR1, and ESR2 genes DNA methylation level in idiopathic scoliosis

Idiopathic scoliosis (IS) is a multifactorial disease with a genetic and environmental background. Recent studies suggest that epigenetic modifications, such as DNA methylation, may contribute to the IS occurrence and course. The aim of this study was to evaluate the association of LBX1, ESR1, and ESR2 gene methylation levels with susceptibility to and severity of IS. The study group (N = 63) consisted of 56 female and 7 male IS patients. The patients were analyzed in two subgroups based on the Cobb angle: ≤ 75° (N = 36) and > 75° (N = 27). The control group (N = 30) consisted of 27 females and 3 males without IS (23 healthy females, 2 spondylolisthesis, 3 scoliosis from prior thoracotomy, and 2 patients with Scheuermann's disease). DNA was isolated from peripheral blood. The methylation of selected LBX1, ESR1, and ESR2 regions was evaluated with a pyrosequencing method. The methylation level was expressed as a percentage of methylated CpG sites. P-value < 0.05 was considered significant. The mean methylation of the LBX1 forward strand promoter region differed significantly between controls 25.81% and patients 20.77%, p = 0.0013. The methylation was significantly higher in controls in 11 of 15 CpG sites. The mean methylation of the ESR1 T-DMR2 region was 50.44% in controls and 54.68% in patients, p = 0.0003. The methylation was significantly lower in controls in 5 of 8 CpG sites. There was no significant difference in the mean methylation level in ESR2 exon 0 N 5.17% vs. 5.58%, p = 0.2057. However, the methylation level in 10 of 19 CpG sites was significantly lower in controls and higher in 4 of 19 CpG. We observed no differences in the methylation level within all analyzed regions of ESR1, ESR2, and LBX1 genes between IS patients with ≤ 75° of the Cobb angle versus > 75°. Significant differences in the LBX1, ESR1, and ESR2 methylation levels between IS patients and controls were identified. IS patients revealed lower LBX1 forward strand promoter region methylation levels compared to controls. No association was found between the LBX1, ESR1, or ESR2 methylation levels and the severity of IS.