RP2-associated retinal disorder in a Japanese cohort: Report of novel variants and a literature review, identifying a genotype-phenotype association.

American journal of medical genetics. Part C, Seminars in medical genetics 2020 Sep

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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. © 2020 The Authors. American Journal of Medical Genetics Part C: Seminars in Medical Genetics published by Wiley Periodicals LLC.

Citation

Kaoru Fujinami, Xiao Liu, Shinji Ueno, Atsushi Mizota, Kei Shinoda, Kazuki Kuniyoshi, Yu Fujinami-Yokokawa, Lizhu Yang, Gavin Arno, Nikolas Pontikos, Shuhei Kameya, Taro Kominami, Hiroko Terasaki, Hiroyuki Sakuramoto, Natsuko Nakamura, Toshihide Kurihara, Kazuo Tsubota, Yozo Miyake, Kazutoshi Yoshiake, Takeshi Iwata, Kazushige Tsunoda, Japan Eye Genetics Consortium Study Group. RP2-associated retinal disorder in a Japanese cohort: Report of novel variants and a literature review, identifying a genotype-phenotype association. American journal of medical genetics. Part C, Seminars in medical genetics. 2020 Sep;184(3):675-693