Abnormal TNS3 gene methylation in patients with congenital scoliosis

Background: Congenital scoliosis (CS) is a congenital deformity of the spine resulting from an abnormal and asymmetrical development of vertebral bodies during pregnancy. However, the etiology and mechanism of CS are still unclear. Epigenetics is the study of heritable variations in gene expression outside of changes in nucleotide sequence. Among these, DNA methylation is the longest known, most characteristic, and most stable epigenetic mechanism. Although methylation is well studied in various complex diseases, its association with CS has not been studied Methods Two pairs of monozygotic twins were included and each had one patient with CS and one without. Agilent SureSelect XT Human Methyl-Sequencing were used for genome methylation sequencing. MethylTarget was used to detect methylation levels in the target regions. Immunohistochemistry was performed to visualize the expression of associated genes in the candidate regions. Results A total of 75 differentially methylated regions were identified, including 24 with an increased methylation level and 51 with a decreased methylation level in the CS group. Nine of the differentially methylated regions were selected ( TNS3 , SEMAC3 , GPR124 , MEST , DLK1 , SNTG1 , PPIB , DEF8 , and GRHL2 ). The results showed that the methylation level of the promoter region of TNS3 was 0.72 ± 0.08 in the CS group and 0.43 ± 0.06 in the control group (p = 0.00070 < 0.01). There was no significant difference in the degree of methylation of SEMAC3 , GPR124 , MEST , DLK1 , SNTG1 , PPIB , DEF8 , or GRHL2 between the two groups. The immunohistochemical results showed that TNS3 expression was significantly decreased in the cartilage of the articular process in CS (CS: 0.011 ± 0.002; control: 0.018 ± 0.006, P = 0.003 < 0.01). Conclusion Compared with the control group, high-level methylation in the TNS3 promoter region and low TNS3 expression in the cartilage layer of the articular process characterized CS patients. This phenomenon may suggest that DNA methylation as well as TNS3 play important roles in the pathogenesis of CS.