Association of the LBX 1 Gene Promoter Methylation in Deep Paraspinal Muscles of Patients with Idiopathic Scoliosis with Disease Severity

Piotr Janusz¹ , Małgorzata Tokłowicz² , Mirosław Andrusiewicz² , Małgorzata Kotwicka² , Tomasz Kotwicki¹

1) Department of Spine Disorders and Pediatric Orthopedics, Poznan University of Medical Sciences 2) Department of Cell Biology, Poznan University of Medical Sciences

Introduction

Idiopathic scoliosis (IS) is a multifactorial disease with significant genetic background. The LBX1 gene polymorphisms are associated with IS. However the pathogenesis of this phenomenon is not established. Epigenetic modifications alter genes expression but do not change the DNA sequence. In recent years, the role of epigenetic factors in the etiopathogenesis of IS has been increasingly investigated.

Research Question

The aim of this study was to evaluate the association of the LBX1 promoter methylation level in deep paraspinal muscles of patients with idiopathic scoliosis with disease severity.

Methods

The study involved 57 girls (171 tissue samples from deep paravertebral muscles, both on the convex and the concave side of the curve and back superficial muscles) who underwent an operation due to IS. Patient subgroups were analyzed according to Cobb angle ≤70° (28 cases) vs. >70° (29 cases).  Level of methylation was evaluated in two promoter regions: proximal (28 CpG sites) and distal (23 CpG sites) using the pyrosequencing method.

Results

The methylation level within proximal promoter region was higher in patients with Cobb angle >70° than in patients with Cobb angle ≤ 70° in 22 of 28 analyzed CpGs (P < 0.05) at the convex side and in 1 of 28 analyzed CpGs (P < 0.05) at the concave side.  There was no difference in superficial muscles between the groups.

The methylation level within distal promoter region was higher in patients with Cobb angle >70° than in patients with Cobb angle ≤ 70° in 3 of 23 analyzed CpGs (P < 0.05) at the convex side, in 7 of 23 analyzed CpGs (P < 0.05) at the concave side and in 7 of 23 analyzed CpGs (P < 0.05) at the superficial muscles.

Conclusions

The level of DNA methylation at the LBX1 promoter region in deep paravertebral muscle tissue may be associated with the severity of idiopathic scoliosis.

Discussion

The risk of developing scoliosis and curvature progression is the result of an additive effect of genetic and the impact of environmental factors. This study revealed a new factor associated with a tendency to scoliosis progression.

Disclosures (any Conflicts of Interest)

The authors declare that they have no competing interests. This study was supported by the National Science Centre grant 2016/23/D/NZ5/02606.