CLOCK and Stroke: In this regard, the DNA methylation patterns of a set of core clock genes, comprising NPAS2, was found modified in patients suffering from ischemic strokes when previously exposed to particulate matter (PM2.5 exposure before the event).These epigenetic traits are impacted by environmental factors, such as pollutant exposure, and suggest the possibility that epigenetic changes in circadian genes could contribute to stroke development or alternatively could be used as prognostic marker of strokes [136].