Interestingly, several of the AMD- (e.g. C3, APOE and TGFBR1) and DR-associated risk genes (e.g. PLXDC2 and ARHGAP22) were preferentially expressed in retinal microglia, which may indicate a role of retinal microglia in disease occurrence and progression. The gene discussed is APOE; the disease is age-related macular degeneration.