汉族常染色体显性视网膜色素变性一家系的连锁分析及突变筛查

摘要

背景 原发性视网膜色素变性(RP)有明显的遗传异质性和表型异质性,目前已确定的致病基因较多,确定患病家系的致病基因是进行基因治疗的基础. 目的 对患常染色体显性遗传性RP(ADRP)的一个汉族家系进行致病基因的定位和基因突变分析.方法 此家系的5代21名成员纳入研究,包括12例ADRP患者和9名表型正常者.12例患者进一步接受中心视野、间接检眼镜、眼电图(EOG)、视网膜电图(ERG)检查.对22个已知的ADRP致病基因所在染色体位点进行连锁分析,以确定该家系与疾病连锁的染色体区域,随后对该区域附近的候选基因视紫红质(RHO)进行直接测序评估其突变情况. 结果 间接检眼镜检查该家系先证者眼底表现符合原发性RP表现,EOG和ERG表现为波形记录不到,视野呈向心性缩小.两点连锁分析结果显示,该家系致病基因位点与遗传标记D3S1292连锁,在θ=0.0时得到最大优势对数(LOD)值为3.6671.候选的RHO基因直接测序结果发现,该家系所有患者第53位密码子的第2个核苷酸均出现了C→G的突变,致其氨基酸由脯氨酸变为精氨酸(Pro53Arg),而该家系正常成员中未发现此突变. 结论 RHO基因的错义突变Pro53Arg与RP疾病出现共分离现象,可确定为该ADRP家系的致病基因.%Background Retinitis pigmentosa (RP) has the genetic and phenotype heterogeneity.To determine the disease-causing gene is a foundation of gene therapy. Objective This study was to localize the pathogenic gene and screen the gene mutation associated with Han Nationality autosomal dominant retinitis pigmentosa (ADRP) in a Chinese family. Methods Twenty-one families enrolled this study,including 12 patients with ADRP and 9 individuals with normal phenotype.Perimetry,fundus examination,electrooculogram ( EOG ) and electroretinogram (ERG) were performed in 12 patients.Genetic linkage analysis was performed on the subjects in all known genetic loci related to ADRP with a panel of microsatellite markers.Subsequently,the mutation screening of rhodopsin gene was screened by direct DNA sequencing.This study was approved by Ethic Committee of Zhongnan Hospital of Wuhan University.Informed consent was obtained from each subject. Results The fundus appearance of the proband was in accordance with the ADRP,and the EOG and ERG showed undetectable.Contractive visual field also was exhibited in the proband.Linkage analysis showed that the maximum logarithm of the odds(LOD) score reached 3.6671 at marker D3S1292 at recombination fraction θ =0.0.The results of direct DNA sequencing revealed a C→ G transversion mutation at codon 53 in exon 1 of rhodopsin gene,which resulted in a proline to arginine change (Pro53Arg) in 12 patients.However,no similar mutation was found in the unaffected members of this family.Conclusions The missence mutation Pro53Arg in rhodopsin gene cosegregate with the RP disease.It is determined to be a pathogenic factor of this ADRP family.