Abstract
In children with Duchenne muscular dystrophy, color vision losses have been related to dystrophin deletions downstream of exon 30, which affect a dystrophin isoform, Dp260, present in the retina. To further evaluate visual function in DMD children, we measured spatial, temporal, and chromatic red-green and blue-yellow contrast sensitivity in two groups of DMD children with gene deletion downstream and upstream of exon 30. Psychophysical spatial contrast sensitivity was measured for low, middle, and high spatial frequencies with achromatic gratings and for low and middle frequencies with red-green and blue-yellow chromatic gratings. Temporal contrast sensitivity was also measured with achromatic stimuli. A reduction in sensitivity at all spatial luminance contrasts was found for the DMD patients with deletion downstream of exon 30. Similar results were found for temporal luminance contrast sensitivity. Red-green chromatic contrast sensitivity was reduced in DMD children with deletion downstream of exon 30, whereas blue-yellow chromatic contrast sensitivity showed no significant differences. We conclude that visual function is impaired in DMD children. Furthermore, we report a genotype-phenotype relationship because the visual impairment occurred in children with deletion downstream but not upstream of exon 30, affecting the retinal isoform of dystrophin Dp260.
Highlights
Duchenne muscular dystrophy (DMD) is the most common dystrophy disease, which is caused by an alteration in dystrophin
One of the aspects of phenotypes of DMD and its milder allelic variant Becker muscular dystrophy (BMD) are alterations in the electric activity of the retina measured by full-field electroretinogram (ERG)
Chromatic contrast sensitivity In the red-green spatial CSF, control subjects and uDMD patients had higher contrast sensitivity values compared with the dDMD group for all spatial frequencies (0.2 cpd, F = 9.43, p = .002; 0.3 cpd, F = 7.27, p = .003; 0.5 cpd, F = 8.96, p = .002; 0.7 cpd, F = 22.54, p < .001; 1.2 cpd, F = 10.53, p < .001; 2 cpd, F = 19.09, p < .001)
Summary
Duchenne muscular dystrophy (DMD) is the most common dystrophy disease, which is caused by an alteration in dystrophin. The less severe cases may have up to 50% deletions of the total size of the gene If these deletions occur in the central region and do not affect the rod-form region of dystrophin, the connection sites with other proteins, such as actin, may be preserved (Zatz, 2002). One of the aspects of phenotypes of DMD and its milder allelic variant Becker muscular dystrophy (BMD) are alterations in the electric activity of the retina measured by full-field electroretinogram (ERG) These alterations have been found in different studies and vary from 50% to 88% of cases (Blake & Kroger, 2000; Girlanda et al, 1997; Mehler, 2000). In a recent study, which considered the genotypephenotype association found in the ERG evaluation, we measured color discrimination in DMD children
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