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Aims: To characterise the detailed phenotype of “cone dystrophy with supernor mal rod ERG”in a case series of 10 patients. Methods: 10 affected patients were examined clinically and underwent colour fundus photography, with nine undergoi ng detailed electrophysiological testing. Five patients were assessed further wi th fundus autofluorescence (AF)imaging, automated photopic and dark adapted peri metry, and dark adaptometry. Detailed colour vision assessment was performed in six subjects. Blood samples were taken from four patients for DNA extraction and mutation screening of NR2E3was undertaken. Results: The onset of symptoms was i n the first and second decades of life. Subjects presented with reduced central vision and marked photophobia. All individuals were myopic and colour vision tes ting revealed severely reduced colour discrimination predominantly along the red -green axes; tritan colour vision was relatively well preserved. Nyctalopia is a later feature of the disorder. Funduscopy and AF imaging revealed a range of m acular appearances. There was electrophysiological evidence of marked macular dy sfunction, reduced and delayed cone responses, and supernormal and delayed rod r esponses. Photopic and dark adapted perimetry revealed central scotomata with wi despread peripheral sensitivity loss. No disease causing sequence variants in NR 2E3 were identified. Conclusions: The largest case series to date has been descr ibed of the clinical, psychophysical and electrophysiological characteristics of this unusual cone dystrophy with supernormal rod responses. Electrophysiologica l data were consistent with a post-phototransduction, but pre-inner nuclear la yer, site of dysfunction. While the definitive diagnosis can only be made with e lectrophysiological testing, several characteristics that may increase suspicion of this diagnosis are presented.
Aims: To characterise the detailed phenotype of “cone dystrophy with supernor mal rod ERG” in a case series of 10 patients. Methods: 10 affected patients were examined clinically and underwent fundourus photography, with nine undergoi ng detailed electrophysiological testing. Five patients were Detailed further wi th fundus autofluorescence (AF) imaging, automated photopic and dark adapted peri metry, and dark adaptometry. Detailed color vision assessment was performed in six subjects. Blood samples were taken from four patients for DNA extraction and mutation screening of NR2E3was undertaken. Results: The onset of symptoms was in the first and second decades of life. Subjects presented with reduced central vision and marked photophobia. All individuals were myopic and color vision tes ting revealed severely reduced color discrimination predominantly along the red-green axes; tritan colour vision was relatively well preserved. Nyctalopia is a later feature of the disorder. F unduscopy and AF imaging revealed a range of m acular appearances. There was electrophysiological evidence of marked macular dy sfunction, reduced and delayed cone responses, and supernormal and delayed rod responses. Photopic and dark adapted perimetry revealed central scotomata with wi despread peripheral sensitivity loss . Conclusions: The largest case series to date has been descr ibed of the clinical, psychophysical and electrophysiological characteristics of this unusual cone dystrophy with supernormal rod responses. Electrophysiologica l data were consistent with a post -phototransduction, but pre-inner nuclear la yer, site of dysfunction. While the definitive diagnosis can only be made with e lectrophysiological testing, several characteristics that may increase suspicion of this diagnosis are presented.