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M. Nakamura, K. Lin, S. Ito, H. Terasaki, Y. Miyake; Novel NYX Mutations and Clinical Phenotype in Japanese Patients with Complete Congenital Stationary Night Blindness . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2314.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The complete type of congenital stationary night blindness (CSNB) is a subtype of Schubert-Bornschein type of CSNB, in which the fundus is essentially normal. (Arch Ophthalmol. 1986;104:1013-20). Recently the leucine-rich proteoglycan nyctalopin gene (NYX) was identified as the mutated gene in complete CSNB (Nat Genet. 2000;26:319-323,324-327). The aim of this study is to report mutations of the NYX gene in Japanese patients with complete CSNB and to describe the clinical features in the patients. Methods: Twelve patients from 10 separate Japanese families with complete CSNB were examined. Genomic DNA was extracted from leukocytes of the peripheral blood, and all 3 exons of the NYX gene were amplified by polymerase chain reaction and directly sequenced. A complete ophthalmologic examination was performed including best-corrected visual acuity, slit-lamp and fundus examination, fundus photography, and electroretinography. Results: A hemizygous mutation in the NYX gene was identified in 6 patients from 4 families. The identified mutations included two missense mutations (Cys386Arg and Asn246Lys) and an insertion or a deletion in exon 3. Clinically, each patient had essentially normal fundi except for myopic changes, mildly reduced corrected visual acuity, and high myopia. Electrophysiologically, the mixed rod-cone ERG showed a negative configuration with the absence of oscillatory potentials. The rod ERG was nonrecordable, and the photopic responses were normal or mildly reduced. The clinical and electrophysiological features were similar to those in patients without any NYX mutation. None of the 4 families with the mutations showed an X-lined recessive hereditary pattern from their family histories. Conclusions: We have identified 4 novel mutations in the NYX gene in 4 Japanese families with complete CSNB. These results confirmed that some Japanese patients with complete CSNB are caused by a NYX gene mutation. Molecular genetic examination can permit the exact determination of the hereditary patterns in patients with complete CSNB.
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