Fetal Pathogenesis of Scoliosis Suggested by Asymmetry of Gene Expression in Paravertebral Muscles.

Background: The dysfunction of paravertebral muscles may contribute to the development of idiopathic scoliosis. Several candidate genes have been linked to scoliosis, but the underlying mechanisms and cell types remain unclear. Methods: We initially included 40 idiopathic scoliosis cases and 19 controls. Muscle biopsies were obtained bilaterally in the cases, and at least unilaterally in the controls. RNA sequencing, differential gene expression analysis and gene set enrichment analysis were performed between cases and controls, and between convex and concave sides in the cases. Hounsfield units (HU) in paravertebral muscles from preoperative CT were assessed at biopsy sites in cases. Results: Qualified transcriptome analysis included 56 samples (30 convex, 26 concave) from 35 scoliosis cases and 22 samples from 17 controls. Among 14 212 expressed genes included in the downstream analysis, 22 differentially expressed genes were identified between cases and controls and 16 between convex and concave sides. Scoliosis cases showed decreased fetal muscle and immune cells. On the convex side, fibro-adipogenic progenitors, endothelial cell types, satellite cells and myeloid cells were reduced, whereas fetal skeletal muscle cells were increased. Morphological asymmetry was verified by the HU findings. Conclusion: These results indicate asymmetric gene expression profiles between the convex and concave paraspinal muscles and support the hypothesis that idiopathic scoliosis may have a fetal developmental component, with the convex side exhibiting molecular signatures consistent with greater muscle mass.