Since AMD is the leading cause of blindness and low vision in the developed world due to the loss of central vision, events held globally this week recognize its impact in terms of decreased productivity, loss of independence, and reduced quality of life. However, with each year, there is encouraging new research into diagnostics and treatments for this disease in which the macula, the central part of the light-sensitive retina in the back of the eye, deteriorates due to the deposit of proteins called drusen in the “dry” form of the disease and in the later stage neovascular form, which involves the proliferation and leakage of blood vessels.
Featured speaker Gregory Hageman, Ph.D., who serves as the Executive Director of the Center for Translational Medicine at the John A. Moran Eye Center at the University of Utah, spoke about his two-plus decades of National Eye Institute (NEI) funded research into AMD, which he describes as “one of the best characterized genetic diseases” due to a convergence of clinical, biological, and genetic data, the latter of which was derived from the National Institutes of Health (NIH)-funded Human Genome Project.
He noted that a refined understanding of genotype and phenotype associations-clinical, biological, pathological-in disease development is a critical step toward the development of effective diagnostics and therapies. In that regard, his research suggests that AMD is likely multiple diseases with substantial overlap and that it co-segregates with other major systemic diseases. He reported that late-stage AMD can develop independently from either the chromosome 1 or the chromosome 10 genes and that some individuals can develop late-stage AMD in the absence of drusen. This has led him to propose that macular drusen are not significantly associated with pure Chromosome 10-directed AMD. As evidence, he notes that AMD in African Americans is associated with drusen, but neovascularization is rare, likely due to a scarcity of chromosome 10 gene variants, while AMD in Asians is primarily neovascular and drusen are uncommon, likely due to a scarcity of chromosome 1 gene variants.
Additionally, he discussed the association between reticular pseudodrusen and late-stage AMD. Reticular pseudodrusen are macular lesions that are similar in size and distribution to unique choroidal (a vascular layer next to the retina) capillaries called the choriocapillaris. Although the lesions had previously been thought to be AMD-related drusen, advances in imaging techniques have demonstrated it as a separate disease phenotype. In a Utah cohort, the reticular pseudodrusen phenotype is significantly associated with nearly 70 percent of all severe late-stage AMD, is female predominant, and can occur in the absence of both chromosome 1 and chromosome 10 gene variants, suggesting that it may be a new AMD disease entity.
Further Information: http://www.eyeresearch.org/naevr_action/AMD2012.html