视网膜色素变性PRPF-31基因剪接位点突变及其相关表型特征研究

目的 研究一个常染色体显性遗传视网膜色素变性（ADRP）大家系的致病基因及其相关表型特征。方法 应用基因组扫描定位和突变检测法确定该家系的致病基因,并对其进行详细的家系调查,同时选取该家系不同代别中11例有症状的患者和7例无症状的个体,进行视网膜电图（ERG）、多焦视网膜电图（mERG）、心理物理学及荧光素眼底血管造影等检测。结果 在19号染色体PRPF-31基因5号内含子-1处发现一新的剪接位点突变（IVS5—1G→A）。家系中有症状的患者均在10岁以前发病,病情进展快而严重,呈Ⅰ型弥漫性视网膜色素变性（RP）表现。Goldmann视野检查,30岁以上患者动态视野大范围缺损,部分患者仅存颞侧视岛,静态视野阈值无法查出;mERG检测：双眼暗视a、b波振幅极度下降且低平,呈熄灭型;多焦视网膜电图显示双眼黄斑区及其周围视网膜反应密度显著降低;荧光素眼底血管造影显示黄斑中央凹周围色素上皮萎缩,呈“牛眼样”外观。7例无症状者中,1例经mERG、心理物理学及分子遗传学检测,证实其为轻症RP患者,另1例为疾病基因的杂合携带者。结论 PRPF-31基因5号内含子-1剪接位点突变（IVS5—1G→A）是ADRP的一种新的突变位点。该突变所致的ADRP表型主要为Ⅰ型弥漫性RP,同时,还存在基因外显不全和表现度不一的变异性表达。

Splicing site mutation of D19S418 in PRPF-31 gene and its phenotypic characters with autosomal dominant retinitis pigmentosa

OBJECTIVE: To evaluate the disease-causing gene and phenotypic characters of a large family with autosomal dominant retinitis pigmentosa (adRP). METHODS: Disease status and associated ocular abnormalities of eight patients and six unaffected members who represent different generations of this family were assessed by measurement of visual psychophysics, full-field and multifocal electrophysiology (ERG and mfERG) and funds fluorescent angiography (FFA). The DNA samples of nineteen patients and fifteen unaffected individuals in this family were examined by Genome scanning, linkage analysis and mutation detection to identify coding sequence changes. RESULTS: A case with variable, early onset night blindness before 10 years and visual field loss in their teens was found. Macular dystrophy, progressing to a retinitis pigmentosa phenotype was demonstrated in most adult cases. Both a-wave and b-wave amplitudes of photopic and scotopic full-field ERG were marked reduced and nearly non-detectable, demonstrating severe damage of photoreceptor systems. There were two obligate gene carriers in the family which remained asymptomatic in the clinical. But one of them was found with a minimal RP characteristic and the other was normal by examination of fundus and ERG. An unreported splicing site mutation (IVS5-1G > A) was identified in intron 5- acceptor site of PRPF-31 gene on chromosome 19. ERG and molecular genetic findings were consistent with the reclassification of this disease as an autosomal dominant RP. CONCLUSION: It is a novel splicing site mutation that IVS5-1G > A of D19S418 site in PRFP31, the relative phenotypes by which main displayed type I/diffuse has variable expressivity and complex phenotype.