Specifically, HOTAIR is a trans-acting lncRNA that can directly interact with several epigenetic enzymes (e.g., polycomb repressive complex 2; PRC2) to regulate the expressions of multiple genes involved in various disease processes, including cancer progression, ischemic stroke, diabetes, and recently angiogenesis in DR (12, 29, 39, 40). The gene discussed is HOTAIR; the disease is diabetes mellitus.