常染色体显性遗传RP患者视紫红质基因突变的检测分析

Mutation analysis of rhodopsin gene in Chinese with autosomal dominant retinitis pigmentosa

目的研究常染色体显性遗传视网膜色素变性(ADRP)患者视紫红质(RHO)基因的突变特征及其在视网膜色素变性(RP)发病机制中的作用。方法应用变性高效液相色谱分析(DHPLC)技术和直接及克隆测序方法对RHO基因进行突变检测。结果一家系4例ADRP患者RHO基因的第297密码子存在杂合的两种类型密码子(AGC和AGT),该家系的另3名患者未检测到该突变,对照组发现1例此类型沉默型突变。该家系在第3外显子3′端下游第4个碱基处发生C-T转换,其11个成员中该位点呈T纯合子1例,呈杂合子状态8例。对照组发现2例该位点的杂合子状态。结论视紫红质基因Ser-297-Ser突变与RP疾病未出现“共分离”现象,因此该沉默型突变不是该ADRP家系的致病原因,系RHO基因的多态现象。

Objective Retinitis pigmentosa（RP） describes a genetically and clinically heterogeneous group of disorders that are characterized by gradual degeneration of photoreceptor cells. Our research aimed at investigating the pattern of rhodopsin （RHO） gene mutation in Chinese with autosomal dominant retinitis pigmentosa （ADRP） and evaluate their effects in the pathogenesis of RP. Methods Twenty-nine patients and 34 healthy members from 7 Chinese families with ADRP and 35 normal subjects were recruited. Genomic DNA was isolated from peripheral blood. Sequence variants of the entire coding exons of the RHO gene were tested using PCR, denaturing high performance liquid chromatography （DHPLC） and DNA sequencing. Results The Ser-297-Ser mutations in the rhodopsin gene were detected in four affected members of one ADRP family. There were two heterzygously types,or AGC and AGT,which was a silence mutation. No mutation was detected in other three patients and normal members in this family. This silence mutation was also found in one matched control. In addition, C-to-T transition occurred at four bases downstream of the 3＇end of exon 3 in this family. The homozygous was found in one of the 11 members and heterzygous in 8 of the 11 members. The heterozygous was also found in two normal people in matched controls. Conclusion We can not regard the Ser-297-Ser mutation in the rhodopsin gene as the pathogenic factor of this ADRP family,which is the single nucleotide polymorphism of the RHO gene. Further study should be conducted to confirm if it is a reason to lead to RP that C-to-T transition occurring at the fourth bases of downstream of the 3＇ end in exon 3 and whether the occurrence frequency is identical in the normal person and the ADRP patients.