A Comprehensive Clinical and Biochemical Functional Study of a Novel RPE65 Hypomorphic Mutation
A Comprehensive Clinical and Biochemical Functional Study of a Novel RPE65 Hypomorphic Mutation
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DOI：
10.1167/iovs.07-1671
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发表时间：
2008-12-01
影响因子：
4.4
通讯作者：
Redmond, T. Michael
中科院分区：
文献类型：
--
作者：
Lorenz, Birgit;Poliakov, Eugenia;Redmond, T. Michael
目的.视网膜营养不良的晚期发作和进展与一些RPE 65错义突变有关。新的P25 L RPE 65突变的功能后果与其早期儿童表型相关，并与其他致病性错义突变进行比较。除了典型的临床测试，眼底自发荧光（FAF），光学相干断层扫描（OCT），双色阈值视野（2CTP）进行了测量。通过SSCP和直接测序法筛选RPE 65突变。在293 F细胞中测定突变型RPE 65的异构酶活性，并通过类维生素A的HPLC分析进行定量。一个非常温和的表型检测到一个现在7岁的男孩纯合子的RPE 65中的P25 L突变。虽然早期发现异常暗适应，但5岁时的最佳矫正视力为20/20，7岁时为20/30。无眼球震颤。视锥视网膜电图（ERG）可测量，视杆ERG严重降低，FAF非常低。2CTP在暗视条件下主要检测视锥细胞介导的反应，光适应视锥细胞反应比正常值低约1.5个对数单位。高分辨率光谱域OCT显示形态学变化。RPE 65/P25 L转染的293 F细胞异构酶活性降低至野生型RPE 65转染细胞的7.7%，而RPE 65/L22 P转染细胞的异构酶活性降低至野生型RPE 65转染细胞的13.5%。观察到的轻度临床表型与严重亚型突变体RPE 65的残留活性一致。还原成
PURPOSE. Later onset and progression of retinal dystrophy occur with some RPE65 missense mutations. The functional consequences of the novel P25L RPE65 mutation was correlated with its early-childhood phenotype and compared with other pathogenic missense mutations.METHODS. In addition to typical clinical tests, fundus autofluorescence (FAF), optical coherence tomography (OCT), and two-color threshold perimetry (2CTP) were measured. RPE65 mutations were screened by SSCP and direct sequencing. Isomerase activity of mutant RPE65 was assayed in 293F cells and quantified by HPLC analysis of retinoids.RESULTS. A very mild phenotype was detected in a now 7-year-old boy homozygous for the P25L mutation in RPE65. Although abnormal dark adaptation was noticed early, best corrected visual acuity was 20/20 at age 5 years and 20/30 at age 7 years. Nystagmus was absent. Cone electroretinogram (ERG) was measurable, rod ERG severely reduced, and FAF very low. 2CTP detected mainly cone-mediated responses in scotopic conditions, and light-adapted cone responses were approximately 1.5 log units below normal. High-resolution spectral domain OCT revealed morphologic changes. Isomerase activity in 293F cells transfected with RPE65/P25L was reduced to 7.7% of wild-type RPE65-transfected cells, whereas RPE65/ L22P-transfected cells had 13.5%.CONCLUSIONS. The mild clinical phenotype observed is consistent with the residual activity of a severely hypomorphic mutant RPE65. Reduction to