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Z.–B. Jin, X.–Q. Liu, M. Hayakawa, A. Murakami, N. Nao–i; Electroretinographic Findings of Female Carriers and Affected Males in X–Linked Retinitis Pigmentosa Pedigree . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1044.
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© ARVO (1962-2015); The Authors (2016-present)
To study the phenotype with emphasis on electroretinographic findings in X–linked retinitis pigmentosa with a proven RPGR ORF15 mutation.
Twenty–six XLRP patients were clinically diagnosed and identified of pathogenic mutation in RPGR gene. Patients were divided into two groups, heterozygotes (female carriers, age range 9–76yrs, mean, 42.5yrs) and hemizygotes(affected males, age range 18–72yrs, mean 41.4yrs). Clinical data, including best corrected visual acuity, refractive error, full–field ERG with maximum flash and 30 Hz flicker stimuli were analyzed. These parameters were compared in two groups with statistical methods.
Hemizygotes showed greater impairment and earlier deterioration tendency of visual acuity (mean, 0.43) than heterozygotes (mean, 0.65). Heterozygotes showed greater diopters of myopia (–10.68D) than hemizygotes (–4.71D). Interocular difference of refractive error was greater in heterozygotes (p=0.029). Hemizygotes showed significantly smaller ERG responses (a–wave amplitude, 22.17µv, b–wave amplitudes, 52.33µv, 30 Hz flicker amplitude=1.26µv) compared with heterozygotes (118.80µv, 114.10µv, 20.58µv, respectively). Interestingly, heterozygotes showed relatively sharp deterioration of the a–wave with age compared with that of b–amplitude (figures).
It is indicated in our study that high myopia might be the supplemental aid in diagnosing this disease. As the a–wave represents the electric activity of photoreceptors while the b–wave is thought to be effected by a–wave and the functional integrity of the signal transmission in the retina, our findings suggest that heterozygotes have photoreceptor degeneration at the late stage while the functional integrity of signal transmission is relative preserved.
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