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L. Xiao-Ling, B. Lin, Y. Li, S.-H. Chen, S.-N. Hu; A Autosomal Dominant Congenital Stationary Night Blindness and Rod Electrophysiology Attuned in a Big Chinese Family With a Novel Mutation (Ser186Leu) in Rhodopsin. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5316.
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Congenital stationary night blindness (CSNB) is an uncommon inherited retinal dysfunction, in which patients complain of night vision difficulties of a no-progressive nature only and in which generally there is no involvement of day vision. We present the clinical and electrophysiological characteristics of a Chinese family with dominantly inherited congenital stationary night blindness (adCSNB) in which a previously unreported novel mutation (Ser186Leu) in the rhodopsin gene (RHO). The mutation is a C to T missense mutation in codon 186.2 of the RHO gene resulting in a Serine (TCG) to Leucine (TTG) change at amino acid 186 of the rhodopsin protein.
Eight affected family members from four generations were ascertained. Eight affected individuals,who were IX2 (female, 75), X-3 (female, age 63), X-4 (male, 59), X-6(female, 35), XI-17 (male, 27), XI-19(male, 29) and XII-12(male, 13), underwent ophthalmic examination and full field electroretinograghy (ERG). Six affected individuals were recorded the curve of stimuli and response in scotopic condition. The stimuli were delivered in 0.5-log unit steps, that were -2.5db, -2.0db,-1.5db,-1.0db, -0.5db and 0db in turn, the 0db is a standard flash stimulus (3 cd/m2, fix on, plot time 150 ms and backlight off)). Two affected individuals (IX -2, X-4) also underwent dark adaptation test.
Affected individuals reported night blindness from an early age. Visual acuities were normal. Fundal appearances were normal apart from one older patient showing mild dry age related macular degeneration and one patient with moderate diabetic retinopathy. International Society for Clinical Electrophysiology of Vision (ISCEV) standard ERG showed attenuated rod specific responses and reduced electronegative maximal responses, but normal ISCEV cone responses. The curve of stimuli and response in amplitude of b-wave were of reduced amplitude and rod was much less insensitive compared with control group. However, there was no apparent rod component to the dark adaptation curve.
Results from investigation of this family are consistent with an impairment of rod photoreceptor signaling. The ERG findings suggest an abnormality occurring rod pathway incompletely involvement. These findings differ from those families reported previously with dominant CSNB.
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