S.P.62 Ocular characteristics of Duchenne Muscular Dystrophy

Abstract

<h2>Abstract</h2> Electroretinogram (ERG) abnormalities have been described in Duchenne Muscular Dystrophy (DMD). Short isoforms of dystrophin are highly expressed in retina. We sought to expand the retinal phenotypes associated with different DMD genotypes. We studied the ocular characteristics of 16 DMD boys, mean age 9.5years (range 4–15years), glucocorticosteroid (GC) treated, with a range of genotypes: six had mutations at the 5′ end of the gene involving exons 3–13, predicted to affect the full length dystrophin Dp427, seven patients exons 44–57, affecting Dp427 and Dp260, and three patients at the 3′ end, in exon 70, affecting expression of Dp427, Dp260 and Dp71. Visual acuity, colour vision, intra-ocular pressure measures (IOP) and full field ganzfeld flash ISCEV Electroretinograms (ERGs) were assessed. Patients had normal visual acuity, one boy had a red-green colour vision defect, and two had raised IOP due to steroid use. ‘Negative' scotopic ERGs with reduced a:b-wave amplitude ratios were recorded in all patients with mutations involving exons 44–57, one patient with a 8–13 deletion and two patients with the 3′ mutation involving exon 70. The scotopic oscillatory potential (OP2) was reduced in all boys with mutations of exons 44–57, and in one with 8–13. The photopic OP2 was reduced in patients with deletions upstream of exon 30, but preserved in those patients in whom scotopic OP2 was attenuated. Photopic ERG a:b-wave amplitude ratios were reduced across the cohort, including those with 5′ mutations in whom scotopic a:b ratios had been normal. These data show a strong association of mutations downstream of exon 30, the promoter region for Dp260, with abnormal scotopic ERGs. In contrast photopic ERG abnormalities were widespread across all genotypes which may relate to the greater proportion of Dp427, compared with other isoforms, at the synapse of cones to cone on-bipolar cells. Our clinical evaluation also reminds us to monitor IOP during GC treatment.