Color vision phenotype in Duchenne Muscle Dystrophy

Abstract

Abstract: : Purpose: to investigate color discrimination in Duchenne Muscle Dystrophy (DMD). Methods: Three different groups of DMD patients were studied: Group 1: without deletions in the dystrophin gene (n= 10); Group 2: with deletions upstream exon 30 (n= 4); Group 3: with deletion downstream exon 30 (n=15). Control group: 23 age–matched subjects without ophthalmologic alterations. The Cambridge Colour Test (CCT) (Cambridge Research Systems) with a VSG 2/5 card and a Sony Triniton Monitor was used to measure protan, deutan and tritan thresholds (units u’v’ X 103) in a short psychophysical test (Trivector), followed by an 8–vector MacAdam ellipse (area u’v’ units X 106). Patients were examined monocularly in the dominant eye, in a dark room. Statistical analyses were performed with the Kruskail–Wallis ANOVA on Ranks. Results: The average and standard deviations of color discrimination thresholds are shown in the table below. Impairment in color vision was statistically significant for all Trivector parameters (Protan p< .001; Deutan p= .003; Tritan p= .002) and for the ellipse area (p= .003). The Dunn’s Multiple Comparison test revealed that controls differ from group 3. Conclusions: To our knowledge, this is the first time color vision is the focus of a study in DMD. Although color vision is not within the functions that are considered to be impaired in DMD, almost all DMD patients showed diffuse impairments in color vision discrimination. Patients with deletion downstream exon 30, which causes impairment in the synthesis of Dp260, an isoform of dystrophin expressed in the outer plexiform layer, showed the largest color vision losses. mean (standard deviation) of the threshold discrimination 

Keywords: color vision • genetics • retina