Transcript of "OOG/ZOG: Van huet foveal sparing in patienten met m. stargardt"
Foveal sparing in patients with Stargardt disease Ramon van Huet OOG/ZOG Hotel Val Monte December 1st, 2012
Introduction | Foveal sparing• Macular atrophy that spares the fovea• Atrophy surrounds the fovea for at least 180
Introduction | Foveal sparing in Stargardt patientsFoveal sparing is observed in:• Stargardt disease• Maternally Inherited Diabetes & Deafness (MIDD)• Age-related macular degeneration (AMD)• Some PRPH2 (RDS) related diseases (e.g. pseudostargardt phenotype)
Introduction | Purpose• To give a clinical description of foveal sparing in Stargardt patients• Provide some possible pathogenic pathways• Knowledge about the origin of the foveal sparing may be beneficial for the development of new therapeutic options
Methods | Patients 13 STGD1 patients with 149 patients foveal sparing who are genetically Database: analysed 136 patients without foveal 316 patients sparing 167 patients without genetic analyses
Methods | ParametersHistory• Age of onset• Initial symptom• Family historyOphthalmic examinations• Visual acuity• PerimetryImaging• Fundus photographs• Autofluorescence• OCT scans
But what causes this preservation of the foveal area??
Discussion | Possible causes of foveal sparingLate-onset Stargardt is on the mild side of the spectrum of retinal dystrophies caused by mutations in ABCA4Fovea spared because of:• Only one ABCA4 mutation• Mild mutations in ABCA4 Late-onset Stargardt
Discussion | Possible causes of foveal sparingInfluence of other genes:• Protective variants in modifier genes• Digenic phenotype On which cells/structures do these additional genes act? RPE? Photoreceptors? Müller cells? The ABCA4 gene? The ABCR channel? (Modifier) ABCA4 Gene X ABCR
Discussion | Possible causes of foveal sparing • Inhomogeneity in distribution of spectrally different cones Sparing of L- and M- cones which are more centrally located1 • Inhomogeneity in distribution of RPE cells In the macula, RPE cells are thicker and narrowly spaced.11. D. Besch et al, Vision research 43 (2003) p. 3095-3108
Discussion | Possible causes of foveal sparing • Inhomogeneity in distribution of the Müller cells Differences in Müller cell density in fovea and periphery1 Various types of Müller cells21. Chao et al, (1997) Journal of Neurocytology 26(7), p.439-4542. Schnitzer et al (1987) Cell Tissue Research 248(1), 55-61
AcknowledgementsOphthalmologyMuhamad MuhamadCarla WestenengJeroen KleveringCarel HoyngHuman geneticsFrans CremersAnneke den Hollander
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