香港地区汉族人视紫红质基因和视网膜色素变性1基因与视网膜色素变性的双基因关联分析

目的研究视紫红质基因(RHO)和视网膜色素变性1(RP1)基因在香港地区汉族视网膜色素变性(RP)患者中的突变频率及特征,并进一步探讨它们在RP发病机理中潜在的相互作用。方法运用高通量构象敏感凝胶电泳和直接测序方法,对151例香港地区汉族RP先证者和150名对照者进行了RHO和RP1基因全编码区和邻近剪切位点的内含子区域序列突变的检测。对携带基因突变的12例RP先证者的46名亲属进一步作分离分析。运用单因素分析、多因素分析和基因型家系不平衡分析研究RHO和RP1基因对RP的作用。结果RHO基因和RP1基因的突变检出率各为1.3%。RHO基因中-26G>A可增高RP危险性,而RP1基因中R872H则可降低RP危险性。多因素Logistic回归分析揭示了RHO基因IVS423G>A分别与RP1基因N985Y和C2033Y之间存在相互作用。结论在香港地区汉族RP患者中,RHO和RP1基因的突变率比其他人群中RP患者的突变率低。除了致病性基因突变,非编码区的序列改变也可改变RP的易感性。部分RP患者由双基因突变引起,当然多基因共同作用也完全可能存在。

Digenic association of RHO and RP1 genes with retinitis pigmentosa among Chinese population in Hong Kong

Objective To identify the mutation patterns of RHO and RP1 genes in the Chinese patients with retinitis pigmentosa (RP) and to explore their potential interactions in the pathogenesis of RP. Methods Sequence alterations in the entire coding region and splice sites of RHO and RP1 gene were screened in 151 RP affected probands and 150 unrelated controls who were all Hong Kong Chinese. Additional 46 relatives of 12 RP probands carrying possible mutations in RHO or RP1 were recruited for segregation analysis. Univariate analysis, multivariate analysis and genotype-pedigree disequilibrium test were used to examine the associations of polymorphisms in these two genes with RP. Results Two mutations in the RHO gene, 5211delC and P347L, were identified each in one proband from the 151 probands, accounting for 1.3% of the RP patients. Two mutations in the RP1 gene, R677X and D984G, were identified each in one proband from the 151 probands, also accounting for 1.3% of the RP patients. In univariate analysis, non-coding sequence variants in the RHO gene, -26G>A, was found to increase the risk of RP, while R872H in the RP1 gene was likely to be a protective factor for RP. Multivariable logistic regression analysis and haplotype analysis confirmed these associations. Conclusion The prevalences of RHO and RP1 mutations among the RP patients in Chinese population are both less than reported in other populations. Besides the disease-causing mutations, non-coding sequence alterations may also be a modifier for RP. The potential interactions between RHO and RP1 suggest a digenic etiology for RP.