LMX1A基因多态性与中国汉族人群先天性脊柱侧凸遗传易感性的关联

Association of LMX1A gene polymorphisms with susceptibility to congenital scoliosis in a Chinese Han population

背景:先天性脊柱侧凸是由于胚胎期脊柱椎体发育异常引起的脊柱侧凸,其遗传病因学假说开始引起许多学者的重视。目的:通过候选基因LMX1A上关键单核苷酸多态性位点的筛查,探索LMX1A与中国汉族人群先天性脊柱侧凸及其不同临床表型之间的关联。方法:入选127例中国汉族先天性脊柱侧凸患者,另选取外伤、感染、炎症性疾病等患者127例为对照组。根据国际人类基因组单体型图计划提供的基因型数据,应用Haploview 4.1软件选取LMX1A的标签和功能单核苷酸多态性位点。根据椎体畸形特点、畸形部位、畸形受累程度、有无合并肋骨畸形和椎管内畸形将病例组进一步分为不同临床表型。所有样本应用SNPstream UHT Genotyping系统对所选单核苷酸多态性位点进行基因型鉴定;进一步进行基于基因型/等位基因频率的关联分析,并用Haploview 4.1软件分析对照组单核苷酸多态性位点间是否存在连锁不平衡。结果与结论:共筛选6个位点:SNP1(rs 1819768)、SNP2(rs 12023709)、SNP3(rs 16841013)、SNP4(rs 4656435)和SNP5(rs 4657412)和SNP6(rs 4657411),其基因型分布在病例组和对照组中均符合Hardy-Weinberg平衡;在基于基因型的关联分析中发现阳性位点SNP1和SNP2,单位点分析显示两位点基因型在病例组和对照组中的分布频率差异有显著性意义(P=0.026和P=0.026),在进一步非条件Logistic回归分析中发现这两个位点的基因型分布最符合Ressessive(OR=0.38;95%CI=0.15～0.94,P=0.029,AIC=354.9)遗传模型;SNP1、SNP2、SNP3和SNP6处于连锁不平衡状态,SNP4和SNP5也处于完全连锁不平衡状态,但单倍体型与先天性脊柱侧凸的发生风险之间不存在相关性;在进一步与先天性脊柱侧凸临床表型的关联分析中发现SNP1基因型AC型、SNP2基因型AG型、SNP3基因型CT型与有椎体形成障碍先天性脊柱侧凸的易感性升高有关。结果提示在中国汉族人群中LMX1A基因可能和先天性脊柱侧凸的发生、发展相关,是一个重要的易感基因。

BACKGROUND：Congenital scoliosis（CS） is caused by the abnormal development of embryonic spinal vertebrae,and its genetic etiology hypothesis has begun to attract the attention of many scholars.OBJECTIVE：To investigate whether polymorphisms of LMX1A gene are associated with CS in a Chinese Han population,and further,to study the relationship between polymorphisms of LMX1A and the clinical phenotypes of CS.METHODS：A total of 127 patients diagnosed with CS and the scoliosis-free control subjects（127 cases） were enrolled in this study.Genomic Based on genotype data from the International HapMap project,the key single nucleotide polymorphisms（SNPs） initially were selected using Haploview 4.1 software.Hardy-Weinberg equilibrium both in control and in case groups was analyzed.Case group were classified into different clinical phenotypes according to vertebral defect type,the location of deformity,the extent of developmental disruption,combined rib malformations and neural canal deformity.Genotying of all selected SNPs was done by SNPstream technology（Beckman Coulter SNPstream）.All the data of SNPs with polymorphism are analyzed by the association analysis based on a single SNP.And pairwise linkage disequilibrium was calculated in the control population using Haploview 4.1 software.RESULTS AND CONCLUSION：Six SNPs of LMX1A gene（SNP1：rs1819768,SNP2：rs12023709,SNP3：rs16841013,SNP4：rs4656435,SNP5：rs4657412,SNP6：rs4657411） were genotyped and all polymorphisms were in Hardy-Weinberg equilibrium both in control and in case groups.The single locus analysis revealed the genotype distributions of SNP1 and SNP2 were statistically significantly different between case patients and control subjects（P=0.026 and P=0.026）.In the unconditional logistic regression analysis,SNP1 and SNP2 both showed significant difference in both Ressessive model（OR=0.38;95%CI=0.15-0.94） and overdominant model（OR=1.73;95%CI=1.05-2.8）,and the P values were 0.029 and 0.032,respectively.The Ressessive model was accepted as the best inheritance model because of the smaller AIC（Akaike information） value（354.9）.SNP1,SNP2,SNP3 and SNP6 were in strong linkage disequilibrium.Both SNP4 and SNP5 were also in strong linkage disequilibrium.But no association was observed between all haplotypes polymorphisms and risk of CS.In the association analysis between the genotyhpes and the phenotype 1（according to vertebral defect type） of CS,we got 3 positive SNPs.SNP1,SNP2 and SNP3 polymorphisms of LMX1A gene may related to CS with failure of formation.In the association analysis between the genotyhpes and other phenotypes of CS,no positive SNPs were obtained.It was suggested that genetic variants of LMX1A gene may be associated with the susceptibility to CS and different clinical phenotypes of CS in the Chinese Han population.