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Christine A Kiire, Suzanne Broadgate, Stephanie Halford, Victor Chong; Genotype-phenotype correlation of diabetic macular edema in type 2 diabetes. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1461.
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© ARVO (1962-2015); The Authors (2016-present)
The prevalence of type 2 diabetes mellitus (T2DM) is increasing rapidly worldwide. As a result there may be a rise in the prevalence of sight-threatening diabetic macular edema (DME). Although efforts have been made to optimise treatment for all forms of DME, there are still patients who do not respond well to the currently available treatments.<br /> <br /> Advances in retinal imaging technology, such as the development of spectral domain optical coherence tomography (SD-OCT), have enabled non-invasive subclassification of DME into phenotypes that might have different underlying pathogeneses or genetic risk factors. On SD-OCT, the cystoid form of DME, with eversion of the fovea (FE), resembles cystoid macular edema due to inflammatory eye conditions such as uveitis. There is evidence to suggest that it might have a different cytokine profile to other forms of DME and that it might respond differently to laser treatment.<br /> <br /> The genetic profile of diabetic retinopathy (DR) has previously been studied in a range of populations without always investigating the genetic risk factors specific to DME. We set out to determine whether the genetic profile of T2DM patients with a history of DME differs from that of those without a history of DME and whether the genetic profile of those with FE might be different from that of those without FE.
A candidate gene analysis of 55 single nucleotide polymorphisms (SNPs) that had previously been associated with DR or DME was performed in 263 British Caucasian T2DM patients. Sequenom sequencing was used for genotyping. Participants were divided into those with and without a history of DME and, of the 130 with DME, into those with and without a history of FE, on the basis of findings on SD-OCT. The presence of vitreomacular traction (VMT), widely accepted to cause DME by a different mechanism to other forms of DME, was also determined.
Two SNPs within the VEGF gene (rs2010963 and rs699946) approached an association with DME (p = 0.0238 and p = 0.0387, respectively) when participants with VMT were excluded. MCP-1 rs4586 approached an association with FE (p < 0.0486) when those with VMT were excluded. These findings were no longer significant after correction for multiple testing.
The role of VEGF SNPs in the heritability of the DME phenotype of DR, and the role of MCP-1 SNPs in the heritability of FE, might be worth further investigation in a larger patient population.
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