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A. Ambresin, L. El Matri, O. Charfi, Y. Arsenijevic, F. Borruat, A. Kawasaki, A. Wenzel, M.W. Seeliger, D.F. Schorderet, F.L. Munier; Further Characterization of a Severe Autosomal Recessive Retinal Dystrophy Caused by R91W Homozygous Mutation in the RPE65 Gene . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1475.
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Purpose: To characterize homozygote and heterozygote members within three nuclear consanguineous families carrying the same R91W mutation in the RPE65 gene based on visual function, full field electroretinography (ERG) and pupillometry (PM). Methods: The R91W mutation was confirmed in 11 homozygotes and 9 heterozygoteswho underwent complete ophthalmologic examination and when possible visual field, fluorescein angiography (FA), ERG and PM. Results: All affected members had useful vision in the first decade of life and progressively lost vision in the third decade of life to the point of disability. Eleven homozygotes were aged 18 to 55 years with acuities ranging from CF to NLP. All had nystagmus. Retinal findings were subdivided into two classes. Class 1 included mid-peripheral drusen-like deposits, absence of pigmented clumps. Class 2 included mid peripheral pigmented clumps and absence of drusen-like deposits. Patients class 1 had better vision than patients class 2. Mean age in class 1 was 29±12.02 years and 47±5.45 years in class 2 (p=0.03). ERG obtained in the 8 homozygotes showed absence of photopic and scotopic responses. Evaluation of the pupillary light reflex revealed diminished contraction amplitude, prolonged latency times and decreased contraction velocity in 3 homozygotes with poor vision. One additional homozygote had subnormal reactivity with only a minimal prolongation of the pupillary latency time. Eleven heterozygotes were aged 34 to 86. All had normal vision except one who was diabetic and had high myopia and age-related cataract. None had nystagmus. Visual acuities range from 20/200 to 20/20. Funduscopy and ERG were normal in 2 heterozygotes tested. Pupillometry was normal in 2 heterozygotes. A third heterozygote (diabetic) had a minimally prolonged pupillary latency time in both eyes. Conclusions: The significant difference in age between the two retinal classes suggested that they may represent a continuum in the evolution of the disease. Homozygotes of both class 1 and 2 showed a complete loss of ERG responses and an abnormal pupillary light reflex. All heterozygotes showed normal visual function including ERG and pupillometry except for one diabetic patient.
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