The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Samir S Deeb - One of the best experts on this subject based on the ideXlab platform.
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polymorphism in red photopigment underlies variation in Colour matching
Nature, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:GENETIC variation of human senses within the Normal range probably exists but usually cannot be investigated in detail for lack of appropriate methods. The study of subtle perceptual differences in red–green Colour Vision is feasible since both photo-pigment genotypes and psychophysical phenotypes can be assessed by sophisticated techniques. Red–green Colour Vision in humans is mediated by two different visual pigments: red (long-wavelength sensitive) and green (middle-wavelength sensitive). The apoproteins of these highly homologous photopigments are encoded by genes on the X chromosome1. Colour matches of males with Normal Colour Vision fall into two main groups that appear to be transmitted by X-linked inheritance2–6. This difference in Colour matching is likely to reflect small variations in the absorption maxima of visual pigments7–11 suggesting the presence of two common variants of the red and/or green visual pigments that differ in spectral positioning5,6. We report that a common single amino-acid polymorphism (62% Ser, 38% Ala) at residue 180 of the X-linked red visual pigment explains the finding of two major groups in the distribution of Colour matching among males with Normal Colour Vision.
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Defective Colour Vision associated with a missense mutation in the human green visual pigment gene.
Nature genetics, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:All red/green Colour Vision defects described so far have been associated with gross rearrangements within the red/green opsin gene array (Xq28). We now describe a male with severe deuteranomaly without such a rearrangement. A substitution of a highly conserved cysteine by arginine at position 203 in the green opsins presumably accounted for his Colour Vision defect. Surprisingly, this mutation was fairly common (2%) in the population but apparently was not always expressed. In analogy with nonexpression of some 5'green-red hybrid genes in persons with Normal Colour Vision, we suggest that failure of manifestation occurs when the mutant gene is located at a distal (3') position among several green opsin genes. This mutation might also predispose to certain X-linked retinal dystrophies.
Jelka Brecelj - One of the best experts on this subject based on the ideXlab platform.
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chromatic vep in children with congenital Colour Vision deficiency
Ophthalmic and Physiological Optics, 2010Co-Authors: Manca Tekavcic Pompe, B Stirn Kranjc, Jelka BreceljAbstract:Visual evoked potentials to chromatic stimulus (cVEP) are believed to selectively test the parvocellular visual pathway which is responsible for processing information about Colour. The aim was to evaluate cVEP in children with red-green congenital Colour Vision deficiency. VEP responses of 15 Colour deficient children were compared to 31 children with Normal Colour Vision. An isoluminant red-green stimulus composed of horizontal gratings was presented in an onset-offset manner. The shape of the waveform was studied, as well as the latency and amplitude of positive (P) and negative (N) waves. cVEP response did not change much with increased age in Colour deficient children, whereas normative data showed changes from a predominantly positive to a negative response with increased age. A P wave was present in 87% of Colour deficient children (and in 100% of children with Normal Colour Vision), whereas the N wave was absent in a great majority of Colour deficient children and was present in 80% of children with Normal Colour Vision. Therefore, the amplitude of the whole response (N-P) decreased linearly with age in Colour deficient children, whereas in children with Normal Colour Vision it increased linearly. P wave latency shortened with increased age in both groups. cVEP responses differ in children with congenital Colour Vision deficiency compared to children with Normal Colour Vision.
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Chromatic VEP in Colour deficient children
Acta Ophthalmologica, 2008Co-Authors: M Tekavcic Pompe, B Stirn Kranjc, Jelka BreceljAbstract:Purpose To compare chromatic VEP response to isoluminant red-green stimulus in children with congenital red-green Colour deficiency with a control group of 30 children with Normal Colour Vision. Methods 15 children (7-18 years) with congenital Colour Vision deficiency (8 in deutan and 7 in protan axis) and 30 healthy children (7-19 years) were included in the study. Colour Vision was assessed with Ishihara plates, Nagel Anomaloscope, Mollon-Reffin Minimalist test, Farnsworth-Munsell D-15 saturated and desaturated test and Farnsworth-Munsell hue 100 test. VEP were recorded to isoluminant red-green stimulus. The stimulus was a 7 deg large circle composed of horizontal sinusoidal gratings, with spatial frequency 2 cycles/deg and 90 % chromatic contrast. VEP were recorded from Oz (mid occipital) position. Children were tested binocularly. Latency and amplitude of positive (P) and negative (N) wave were measured and so was mean amplitude (N-P wave). Results N wave was present in 24/30 children with Normal Colour Vision (110 ± 25.1 ms; 9.7 ± 4.8 μV) and only in 1/15 child with Colour Vision deficiency (93 ms; 3.2 μV). P wave was present in 30/30 children with Normal Colour Vision (138 ± 21.1 ms; 21.1 ± 13.5 μV) and in 13/15 children with Colour Vision deficiency (131.9 ± 6.1 ms; 19.4 ± 10.7 μV). In healthy children waveform changed from predominantly positive to negative wave with increasing age, whereas in Colour deficient children no obvious waveform changes were observed. Conclusion VEP response to isoluminant chromatic stimulus showed different characteristics in children with congenital Colour Vision deficiency compared to children with Normal Colour Vision. manca.tekavcic-pompe@guest.arnes.si
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CERTIFICATION OF Colour Vision IN CHILD
Slovenian Medical Journal, 2004Co-Authors: Manca Tekavcic Pompe, Jelka Brecelj, B Stirn KranjcAbstract:Background. Studies have shown that chromatic information of visual stimulus is conducted and analysed in two major pathways, parvocellular (also named red-green pathway) and koniocellular (also named blue-yellow pathway). They both start in the retinal photoreceptors (cones) and finish in visual cortex. Colour Vision can be tested in several different ways. Subjective psychophysical tests include Ishihara, Farnsworth-Munsell tests and anomaloscope, whereas objective tests include chromatic electroretinography (ERG), which can test cone function and chromatic visual evoked potentials (VEP), which can test parvocellular and koniocellular pathway function. Aim. To introduce a new method by choosing the optimal stimulus, which stimulates selectively parvocellular and koniocellular pathway. To show the stimulus and the signal in a child with Normal Colour Vision and in a child with green deficiency (deuteranomalia). Methods and results. Isoluminant red-green (blue-yellow) stimulus was introduced. The stimulus was 7 deg large, round, composed of horizontal gratings. Spatial frequency was 2 c/deg, frequency of stimulation 1 Hz, onset: offset was 300:700 ms. Two children are presented, a girl with Normal Colour Vision and a boy with deuteranomalia. Characteristic N1 negative wave was significant in girl after red-green and blue-yellow stimulation, whereas in boy with deuteranomalia N1 was absent after blue-yellow and evident after red-green stimulation. Conclusions. Chromatic VEP, as an objective Colour Vision testing method, could have an important role in testing children, therefore its study is important.
Joris Winderickx - One of the best experts on this subject based on the ideXlab platform.
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polymorphism in red photopigment underlies variation in Colour matching
Nature, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:GENETIC variation of human senses within the Normal range probably exists but usually cannot be investigated in detail for lack of appropriate methods. The study of subtle perceptual differences in red–green Colour Vision is feasible since both photo-pigment genotypes and psychophysical phenotypes can be assessed by sophisticated techniques. Red–green Colour Vision in humans is mediated by two different visual pigments: red (long-wavelength sensitive) and green (middle-wavelength sensitive). The apoproteins of these highly homologous photopigments are encoded by genes on the X chromosome1. Colour matches of males with Normal Colour Vision fall into two main groups that appear to be transmitted by X-linked inheritance2–6. This difference in Colour matching is likely to reflect small variations in the absorption maxima of visual pigments7–11 suggesting the presence of two common variants of the red and/or green visual pigments that differ in spectral positioning5,6. We report that a common single amino-acid polymorphism (62% Ser, 38% Ala) at residue 180 of the X-linked red visual pigment explains the finding of two major groups in the distribution of Colour matching among males with Normal Colour Vision.
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Defective Colour Vision associated with a missense mutation in the human green visual pigment gene.
Nature genetics, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:All red/green Colour Vision defects described so far have been associated with gross rearrangements within the red/green opsin gene array (Xq28). We now describe a male with severe deuteranomaly without such a rearrangement. A substitution of a highly conserved cysteine by arginine at position 203 in the green opsins presumably accounted for his Colour Vision defect. Surprisingly, this mutation was fairly common (2%) in the population but apparently was not always expressed. In analogy with nonexpression of some 5'green-red hybrid genes in persons with Normal Colour Vision, we suggest that failure of manifestation occurs when the mutant gene is located at a distal (3') position among several green opsin genes. This mutation might also predispose to certain X-linked retinal dystrophies.
Arno G Motulsky - One of the best experts on this subject based on the ideXlab platform.
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polymorphism in red photopigment underlies variation in Colour matching
Nature, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:GENETIC variation of human senses within the Normal range probably exists but usually cannot be investigated in detail for lack of appropriate methods. The study of subtle perceptual differences in red–green Colour Vision is feasible since both photo-pigment genotypes and psychophysical phenotypes can be assessed by sophisticated techniques. Red–green Colour Vision in humans is mediated by two different visual pigments: red (long-wavelength sensitive) and green (middle-wavelength sensitive). The apoproteins of these highly homologous photopigments are encoded by genes on the X chromosome1. Colour matches of males with Normal Colour Vision fall into two main groups that appear to be transmitted by X-linked inheritance2–6. This difference in Colour matching is likely to reflect small variations in the absorption maxima of visual pigments7–11 suggesting the presence of two common variants of the red and/or green visual pigments that differ in spectral positioning5,6. We report that a common single amino-acid polymorphism (62% Ser, 38% Ala) at residue 180 of the X-linked red visual pigment explains the finding of two major groups in the distribution of Colour matching among males with Normal Colour Vision.
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Defective Colour Vision associated with a missense mutation in the human green visual pigment gene.
Nature genetics, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:All red/green Colour Vision defects described so far have been associated with gross rearrangements within the red/green opsin gene array (Xq28). We now describe a male with severe deuteranomaly without such a rearrangement. A substitution of a highly conserved cysteine by arginine at position 203 in the green opsins presumably accounted for his Colour Vision defect. Surprisingly, this mutation was fairly common (2%) in the population but apparently was not always expressed. In analogy with nonexpression of some 5'green-red hybrid genes in persons with Normal Colour Vision, we suggest that failure of manifestation occurs when the mutant gene is located at a distal (3') position among several green opsin genes. This mutation might also predispose to certain X-linked retinal dystrophies.
Davida Y Teller - One of the best experts on this subject based on the ideXlab platform.
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polymorphism in red photopigment underlies variation in Colour matching
Nature, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:GENETIC variation of human senses within the Normal range probably exists but usually cannot be investigated in detail for lack of appropriate methods. The study of subtle perceptual differences in red–green Colour Vision is feasible since both photo-pigment genotypes and psychophysical phenotypes can be assessed by sophisticated techniques. Red–green Colour Vision in humans is mediated by two different visual pigments: red (long-wavelength sensitive) and green (middle-wavelength sensitive). The apoproteins of these highly homologous photopigments are encoded by genes on the X chromosome1. Colour matches of males with Normal Colour Vision fall into two main groups that appear to be transmitted by X-linked inheritance2–6. This difference in Colour matching is likely to reflect small variations in the absorption maxima of visual pigments7–11 suggesting the presence of two common variants of the red and/or green visual pigments that differ in spectral positioning5,6. We report that a common single amino-acid polymorphism (62% Ser, 38% Ala) at residue 180 of the X-linked red visual pigment explains the finding of two major groups in the distribution of Colour matching among males with Normal Colour Vision.
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Defective Colour Vision associated with a missense mutation in the human green visual pigment gene.
Nature genetics, 1992Co-Authors: Joris Winderickx, Delwin T Lindsey, Elizabeth Sanocki, Davida Y Teller, Arno G Motulsky, Samir S DeebAbstract:All red/green Colour Vision defects described so far have been associated with gross rearrangements within the red/green opsin gene array (Xq28). We now describe a male with severe deuteranomaly without such a rearrangement. A substitution of a highly conserved cysteine by arginine at position 203 in the green opsins presumably accounted for his Colour Vision defect. Surprisingly, this mutation was fairly common (2%) in the population but apparently was not always expressed. In analogy with nonexpression of some 5'green-red hybrid genes in persons with Normal Colour Vision, we suggest that failure of manifestation occurs when the mutant gene is located at a distal (3') position among several green opsin genes. This mutation might also predispose to certain X-linked retinal dystrophies.
