Association Between Osteoprotegerin Gene And Glucose Transporter-1 Gene Single Nucleotide Polymorphisms And Cervical Spondylotic Myelopathy

The morbility of cervical spondylotic myelopathy(CSM) increased in recent years. The patients suffers from CSM becomes younger.The etiological factors of CSM include age,sex,occupation and smoke,et al.But the influence of the height,body weight and heredity is not certain. Researchers have made great progress in the genetic factor for degenerative disc disease, which had changed the traditional idea and made the genetic factor become the main point. The gene therapy for degenerative disc disease has been reported, which based on the gene polymorphisms. The purpose of this study is to investigate the association between osteoprotegerin gene and glucose transporter-1 gene single nucleotide polymorphisms and cervical spondylotic myelopathy, which may provide evidence for the treatment of CSM.Cervical spondylotic myelopathy is common disease in normal clinical work, which has higher morbility in elder people. The symptoms such as limb numb,weakness,or ambulation barrier could influence the normal life or daily work greatly,which threatens patient's health. Cervical disc herniation or bony hyperplasy resulting in spinal cord myelopathy is the main pathological change. Up to now,there have been reported a series of etiological factors such as environmental factors such as age,sex,smoke,dynamic mechanical factors or the cervical anatomic factor such as spinal stenosis.In addition, genetic factors have been taken as the main cause of CSM or other spinal disorders.Osteoprotegerin is a kind of secreted glucoprotein,discovered in 1997, which is one of the TNF superfamily. Osteoprotegerin and RANK, together with RANKL,are the essential regulator of osteoclastgenesis. RANKL sitmulates RANK, which simulates the differentiation and activation of osteoclastgenesis, and stops the apoptisis of osteoclast. Osteoprotegerin stops the osteoclastgenesis as a decoy receptor which stops the combination of RANK and RANKL.Osteoprotegerin gene is one of the most studied genes in the field of low bone density or osteoporosis and related fractures. A number of SNPs such as 209G/A, 163A/G, 245T/G, 889C/T, 149T/C and 950T/C in the promoter region of osteoprotegerin gene have been discovered. As a inhibitor of osteoclastgenesis, osteoprotegerin gene polymorphysims may influence the rebuild and remodeling process. So, osteoprotegerin gene can be taken as a candidate gene for CSM. However, up to date, there is no related report in the literature.Glucose transporter is a kind of transmembrane glycoprotein, mediating the glucose facilitated diffusion, which is the most well studied facilitated diffusion transporter. Glucose transporter-1 is well spread transporter in the body. For the intervertibral disc, glucose transporter-1 is important glucose transporter and regulates the energy metabolism of the disc cell. Glucose transporter-1 not only expresses in the annulus fibrosus, but in the nucleus gelatinosus. The energy for inner part of disc have to be transported from the disc matrix.Then the abnormal express of glucose transporter-1 gene leads to characteristic change of disc, which is the key process of disc degeneration and hernia. So, the mutation of glucose transporter-1 gene is related to the development of CSM.This study is to contrast the genotypes of CSM patients and controls,the aim of which is to investigate the association between osteoprotegerin gene and GLUT-1 gene single nucleotide polymorphysims and CSM.Objectives1,To investigate the association between osteoprotegerin gene 149 and 950 T/C single nucleotide polymorphisms and the development and severity of cervical spondylotic myelopathy in Chinese subjects2,To investigate the association between glucose transporter-1 gene single nucleotide polymorphisms and the development and severity of cervical spondylotic myelopathy in Chinese subjects3,To investigate the association between the genotypes of osteoprotegerin gene 149 T/C and glucose transporter-1 gene by XbaI and the severity of disc degeneration of CSMMethods and ResultsIn the first part of this research, we investigated the difference of genotype and allele of osteoprotegerin gene 149 and 950 T/C SNPs between the cases and controls in order to evaluate the association between osteoprotegerin gene 149 and 950 T/C single nucleotide polymorphisms and the development and severity of cervical spondylotic myelopathy in Chinese subjects. Genomic DNA was extracted from peripheral blood leukocytes using a Genomic DNA Extraction Kit. The genotype and allele were identified by restriction enzyme. The severity of CSM was evaluated by JOA scores and the numbers of segmental lesions calculated from MRI image.χ2-test was used to detect the association between osteoprotegerin gene 149 and 950 T/C single nucleotide polymorphisms and the development and severity of CSM. All the genotype frequencies were in Hardy–Weinberg equilibrium. Significant differences were noted in 149 T/C genotype distribution between the cases and controls. For 149 T/C polymorphism, we observed the cases had a lower prevalence of TT genotype than controls (26.56% vs. 41.15%, P=0.002).The T allele frequencies in controls and cases were 60.16% and 50.00% (P=0.005). The odds ratio for developing CSM was 0.66 for the 149 T/C T allele carriers. For 950 T/C polymorphism, no difference was observed in genotype distribution and the allele frequencies between cases and controls.The result of Binary logistic regression analysis showed the 149 T/C genotype and mean desk work time were independable risk factors for CSM .In the second part of this research, we investigated the difference of genotype and allele of Glut-1 gene SNPs between the cases and controls in order to evaluate the association between Glut-1 single nucleotide polymorphisms and the development and severity of cervical spondylotic myelopathy in Chinese subjects. Genomic DNA was extracted from peripheral blood leukocytes using a Genomic DNA Extraction Kit. The genotype and allele were identified by restriction enzyme. The severity of CSM was evaluated by JOA scores and the numbers of segmental lesions calculated from MRI image.χ2-test was used to detect the association between Glut-1 gene single nucleotide polymorphisms and the development and severity of CSM. All the genotype frequencies were in Hardy–Weinberg equilibrium. Significant differences were noted in genotype distribution and allele frequencies between the cases and controls. For Xx polymorphism, we observed the cases had a higher prevalence of xx genotype than controls (56.3% vs. 21.1%, P=0.000).The x allele frequencies in cases and controls were 67.9% vs. 46.1%, respectively. The odds ratio for developing CSM was 2.45 times for the x allele than X carriers. Subjects carrying xx genotype had nearly five times increased risk for CSM (OR 4.74; 95%CI 3.03-7.41) than subjects carrying Xx or XX genotype. Binary logistic regression analysis for CSM as the dependent variable showed the GLUT-1 SNP by XbaI was independent risk factor for CSM.In the third part of this research, we investigated the association between the genotypes of osteoprotegerin gene 149 T/C and glucose transporter-1 gene by XbaI and the severity of disc degeneration of CSM. The scores of each cervical disc degeneration from MRI T2WI were acquired by Schneiderman's evaluation criterion. The scores of disc degeneration for xx genotype were significantly higher than those for XX and Xx genotype byχ2-test.There were significant difference for the scores of xx contrasted to the XX or Xx genotype. The scores of disc degeneration for GLUT-1 149T/C CCgenotype were significantly higher than those for TT and TC genotype byχ2-test.There were significant difference for the scores of CC contrasted to the TT or TC genotype.ConclusionOur results demonstrate that the 149 T/C SNP of OPG gene may be a genetic risk factor associated with the presence but not the severity of CSM. The 149 T/C SNP and mean desk work time,together with Glut-1gene SNP by XbaI, are independent risk factors for CSM in Chinese subjects. The 950 T/C SNP of OPG gene may not be a genetic risk factor associated with the presence of CSM. Glut-1 gene SNP by XbaI may be a genetic risk factor associated with the presence but not the severity of CSM.The CC genotype of 149 T/C SNP of OPG gene is associated with more severe disc degeneration than TT or TC genotype. The xx genotype of Glut-1 gene SNP by XbaI is associated with more severe disc degeneration than XX or Xx genotype.