The Association Study Between The Polymorphism Of VDR And SNAP23 Gene And Degenerative Disc Disease Of The Lumbar Spine In Northern Han Chinese

1. BackgroundChronic low back pain is a common disorder in orthopedics. Although the causes of low back pain are various, the most common causes are thought to be musculoligamentous injuries and age-related degenerative processes of spinal structures. This age-related degeneration may occur in the disc or the facet joint. If the degeneration is located in the disc, then we call it degenerative disc disease (DDD). DDD can occur in the cervical spine, the thoracic spine and the lumbar spine. The lumbar DDD means the degeneration is located in the lumbar spine. Lumbar DDD is a kind of syndrome that includes prolapse of intervertebral disc, lumbar spinal stenosis, degenerative instability, degenerative slippage, and degenerative scoliosis.It's still unknown about the causes of the aging and degeneration of the disc, while it's believed that many factors may take part in this process, which includes genetic, metabolic, apoptosis and structural injury. Although it's still not sure about the genetic methods of lumbar DDD, it is likely that DDD is a complex/multifactorial disease determined by the interplay between gene(s) and the environment. Some specific genes associated with DDD have been found, such as Vitamin D receptor (VDR), MMP-3, COL, IL, SPARC and so on. At present, the association between these genes and lumbar DDD is still not quite clear, further genetic association studies are needed.2. Objectives(1). To investigate the relationship between VDR polymorphic phenotype and lumbar DDD.(2). To investigate the relationship between SNAP23 polymorphic phenotype and lumbar DDD. 3. Material and Methods:This study is a hospital-based case-control design.(1). Study materialsAccording to the inclusion and exclusion criteria, a total of 118 patients with lumbar DDD and 112 healthy controls were studied. All of the subjects were from Peking Union Medical College Hospital. Meanwell, all of them were han population from north china.(2). Methods①. Genolnic DNA was extracted from peripheral blood leukocyte of each subject who had signed the informned consellt, using QIAamp DNA Blood Mini KIT.②. Single nucleotide polymorphisms were selected. The SNPs were selected according to the previous study and the gene database provied by the NCBI and Human Genome Project. Twenty SNPs of VDR and 4 SNPs of SNAP23 were selected.③. Genotying of all selected SNPs was done by SNPstream technology.④. Analyze the differences of the allele frequency of VDR and SNAP23 between the case group and the control group through Goodness-of-fitChi-square test.⑤. All the data of the SNPs with polymorphism are analyzed by the association analysis.⑥. We use the SNPstats, online software, to analyze all the data of the SNPs with polymorphism by the association analysis based on alleles and phenotypes of SNPs and 95% confidence intervals (Cls) were computed by the unconditional logistic regression to estimate the relative risk for the single locus genotypes.⑦. Haplotype frequencies were estimated and the differences in haplotype distributions between cases and controls were assessed by Haploview 4.1 software.4. Results(1). Twenty-four alleles of 2 genes (VDR and SNAP23) were studied.(2). VDR gene:We failed in composing premier of 1 SNP(rs11574107) and abandoned it in this study.Three SNPs(rs7975232, rs3782905 and rs4237855) of the remained 19 SNPs were out of balance in Hardy-Weinberg equilibrium test of the contrl group.SNAP23 gene:All the 4 SNPs (rs4923947, rs9302112, rs2617236 and rs2595940) were in Hardy-Weinberg equilibrium in the contrl group.(3). Allele frequency between the case group and the control group:VDR gene:The allele frequency distributions of rs2239179 was statistically different between the case group and the control group (P=0.046). The allele "G" may be associated with lumbar DDD.SNAP23 gene:The allele frequency distributions of the 4 SNPs (rs4923947, rs9302112, rs2617236 and rs2595940) were all statistically different between the case group and the control group (P=0.017, P=0.018, P=0.018, P=0.018). The allele "A" of rs4923947, "G" of rs9302112, "T" of rs2617236 and "A" of rs2595940 may be associated with lumbar DDD.(4). Genotypes frequency between the case group and the control group:VDR gene:There was no significant difference of the genotype "G/G" or "A/G" of rs2239179 between the case group and the control group (P=0.251, P=0.203). In the unconditional logistic regression analysis, no SNPs showed significant in Codominant, Dominantand, Recessive, Overdominant or Log-additive model.SNAP23 gene:There were significant differences of the genotype "A/G" of rs4923947, "A/C" of rs2595940, "A/T" of rs2617236 and "A/G" of rs9302112 between the case group and the control group(P=0.039, P=0.040,P=0.040,P=0.040). In the unconditional logistic regression analysis, these 4 SNPs showed significant in Dominantand and Log-additive model.(5). Haplotype frequencies between the case group and the control group: There were significant differences of haplotype frequencies of SNAP23 gene between the case group and the control group, while not of VDR gene.5. Conclusions(1). Genetic variants of VDR gene may not associate with lumbar DDD in a northern Chinese Han population.(2). Genetic variants of SNAP23 gene may be associated with lumbar DDD in a northern Chinese Han population.(3). Genotype "A/G" of rs4923947, "A/C" of rs2595940, "A/T" of rs2617236 and "A/G" of rs9302112 may be the susceptible genetic factors of lumbar DDD.