The retinitis pigmentosa 2 (RP2) gene is one of the causative genes for X‐linked inherited retinal disorder. We characterized the clinical/genetic features of four patients with RP2‐associated retinal disorder (RP2‐RD) from four Japanese families in a nationwide cohort. A systematic review of RP2‐RD in the Japanese population was also performed. All four patients were clinically diagnosed with retinitis pigmentosa (RP). The mean age at examination was 36.5 (10–47) years, and the mean visual acuity in the right/left eye was 1.40 (0.52–2.0)/1.10 (0.52–1.7) in the logarithm of the minimum angle of resolution unit, respectively. Three patients showed extensive retinal atrophy with macular involvement, and one had central retinal atrophy. Four RP2 variants were identified, including two novel missense (p.Ser6Phe, p.Leu189Pro) and two previously reported truncating variants (p.Arg120Ter, p.Glu269CysfsTer3). The phenotypes of two patients with truncating variants were more severe than the phenotypes of two patients with missense variants. A systematic review revealed additional 11 variants, including three missense and eight deleterious (null) variants, and a statistically significant association between phenotype severity and genotype severity was revealed. The clinical and genetic spectrum of RP2‐RD was illustrated in the Japanese population, identifying the characteristic features of a severe form of RP with early macular involvement.

中文翻译：

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RP2相关性视网膜疾病的日本队列：新型变异的报告和文献综述，确定基因型-表型的关联。

色素性视网膜炎2（RP2）基因是X连锁遗传性视网膜疾病的致病基因之一。我们描述了来自全国范围内四个日本家庭的四名RP2相关性视网膜疾病（RP2- RD）患者的临床/遗传学特征。RP2的系统评价在日本人口中也进行了RD。所有四名患者均被临床诊断为色素性视网膜炎（RP）。检查的平均年龄为36.5（10-47）岁，右/左眼的平均视力为最小分辨角对数的1.40（0.52-2.0）/1.10（0.52-1.7），分别。3例表现为黄斑受累的广泛性视网膜萎缩，1例为中央视网膜萎缩。四个RP2鉴定出变体，包括两个新的错义（p.Ser6Phe，p.Leu189Pro）和两个先前报道的截短变体（p.Arg120Ter，p.Glu269CysfsTer3）。两名具有截短变异的患者的表型比两名具有错义变异的患者的表型更严重。系统评价揭示了另外11个变体，包括3个错义变体和8个有害（无效）变体，并且表型严重程度与基因型严重程度之间存在统计学上的显着关联。RP2- RD的临床和遗传谱图在日本人群中得到了阐明，确定了早期黄斑受累的严重形式RP的特征。