MicroRNAs as diagnostic and prognostic biomarkers of age-related macular degeneration: advances and limitations

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Date: Mar. 2021
From: Neural Regeneration Research(Vol. 16, Issue 3)
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Report
Length: 8,029 words
Lexile Measure: 1550L

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Byline: Bridget. Martinez, Philip. Peplow

A main cause of vision loss in the elderly is age-related macular degeneration (AMD). Among the cellular, biochemical, and molecular changes linked to this disease, inflammation and angiogenesis appear as being crucial in AMD pathogenesis and progression. There are two forms of the disease: dry AMD, accounting for 80-90% of cases, and wet AMD. The disease usually begins as dry AMD associated with retinal pigment epithelium and photoreceptor degeneration, whereas wet AMD is associated with choroidal neovascularization resulting in severe vision impairment. The new vessels are largely malformed, leading to blood and fluid leakage within the disrupted tissue, which provokes inflammation and scar formation and results in retinal damage and detachment. MicroRNAs are dysregulated in AMD and may facilitate the early detection of the disease and monitoring disease progression. Two recent reviews of microRNAs in AMD had indicated weaknesses or limitations in four earlier investigations. Studies in the last three years have shown considerable progress in overcoming some of these concerns and identifying specific microRNAs as biomarkers for AMD. Further large-scale studies are warranted using appropriate statistical methods to take into account gender and age disparity in the study populations and confounding factors such as smoking status.

Introduction

A main cause of vision loss in the elderly is age-related macular degeneration (AMD), which profoundly impacts quality of life (Raftery et al., 2007; Chakravarthy et al., 2010; Schaal et al., 2016; Wang et al., 2016a; Al-Zamil et al., 2017). Given the increasing aging population worldwide, the incidence of AMD is projected to increase from 196 million in 2020 to 288 million in 2040 (Wong et al., 2014), placing a significant burden on families and the healthcare system. Demographic, environmental and genetic risk factors all play substantial contributing roles in the pathophysiology of AMD. Among the cellular, biochemical, and molecular changes linked to this disease, inflammation and angiogenesis appear to be critical in AMD pathogenesis and progression (Agrawal and Chaqour, 2014; Kauppinen et al., 2016).

There are two forms of AMD, dry (nonexudative) and wet (exudative, neovascular) (Machalinska et al., 2012). The disease usually begins as the dry type constituting 80-90% of cases, whereas wet AMD represents 10-15% of AMD cases. Dry AMD is associated with retinal pigment epithelium (RPE) and photoreceptor degeneration (Ayoub and Patel, 2009), while wet AMD is associated with choroidal neovascularization and accounts for 90% of clinical cases with severe vision impairment (Bhise et al., 2011; Heiferman and Fawzi, 2019). Characteristic of dry AMD is an altered RPE pigment distribution in the macula, and the generation of pale or yellow deposits called drusen in the space between the RPE and Bruch's membrane (Johnson et al., 2003; Ayoub and Patel, 2009; Algvere et al., 2016). Bruch's membrane is the innermost layer of the choroid and lies in apposition to the RPE. Drusen contain a variety of constituents, including lipid and amyloid-[sz] deposits (Isas et al., 2010). Early stage dry AMD patients may remain asymptomatic and it may take years for their vision to be...

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Gale Document Number: GALE|A636783701