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Kimiko Suto, Katsuhiro Hosono, Yasunori Nagase, Hiroshi Nakanishi, Kunihiro Mizuta, Shinsei Minoshima, Yoshihiro Hotta; Visual Outcomes of Japanese Patients with Retinitis Pigmentosa and Usher Syndrome Caused by USH2A Mutations. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2901.
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© ARVO (1962-2015); The Authors (2016-present)
EYS and USH2A are the most common causative genes for retinitis pigmentosa (RP) in Japan. We analyzed 14 patients with two deleterious USH2A mutations to determine the clinical findings of Japanese patients with RP and Usher syndrome type II (USH2) associated with USH2A mutations. The visual field and visual acuity of patients were tested and compared with those previously reported in association with EYS mutations.
Two nonsyndromic RP patients and 12 USH2 patients with previously identified USH2A mutations were included in this study. The complete history and medical records of the patients were reviewed, and clinical evaluations were performed using standard procedures, including spectral-domain optical coherence tomography (OCT). Electroretinography (ERG) was also performed for some patients. Otolaryngological examination, including audiography, was performed for all patients. Goldmann visual fields scanned with a Canon or Epson scanner were analyzed using ImageJ software, and the field areas of the V-4e targets were measured and compared with the normal areas.
There were six males and eight females with an age range of 12 to 52 years at the time of initial examination. 11 patients had a family history and 3 were isolated cases. All 14 patients had night blindness. In all patients, the fundus displayed changes typical of RP. OCT images also showed a marked decrease in the retinal thickness, resulting from the loss of photoreceptor layers. ERG responses were consistent with severe generalized rod-cone dysfunction. Overall, most patients showed relatively well-preserved visual acuity in their 30s, with rapid deterioration in their 40s or 50s. The constriction of visual fields was symmetric. Concentric constriction initiated in the 20s or 30s, and no effective residual visual field was observed after the 50s. These findings indicated that the visual outcome of RP in patients with USH2A mutations was consistent with that of RP associated with EYS mutations.
RP in Japanese patients with USH2A mutations is characterized by rod-cone dystrophy and shows a poor prognosis after 60 years of age. Further studies with a larger sample size are needed to clarify these findings.
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