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Doyne Honeycomb Degeneration of the Retina
Beginning usually in midlife, the retina has radially localized white, large drusen in the posterior pole. These may begin as small drusen that later enlarge and become confluent creating a honeycomb pattern. The disease begins as an accumulation of material between the Bruch membrane and the RPE. Eventually drusen occupy the entire thickness of the Bruch membrane and are continuous with or internal to the RPE basement membrane. Vision early is normal and a slow loss of vision occurs sometime after the drusen appear in most individuals. In some patients geographic atrophy, pigmentary changes, and a subfoveal neovascular net develops with macular scarring, vitreous hemorrhage, and severe reduction of vision.
No systemic disease is associated.
Doyne honeycomb macular disease, or dominant drusen, is the result of mutations in the EFEMP1 gene at 2p16 in the majority of cases. The mutant protein product (a member of the fibulin famiy) is folded abnormally and secreted inefficiently. It is also resistant to degradation which may lead to receptor damage by limiting access to nutrients from the choriocapillaris. Some genetic heterogeneity may exist since a few cases seem to be linked to a locus at 6q14. It is an autosomal dominant disorder. Some have considered Malattia Leventinese and Doyne honeycomb retinal dystrophy as separate entities but mutations in the same gene seem to be responsible for both conditions suggesting they are clinical variations of the same disorder.
The subfoveal net responds to photodynamic therapy.