New research has filled in missing links between gene variants that have been implicated in disease through genome-wide association studies and how the variants drive disease pathology. The research involved using induced pluripotent stem cells derived from healthy donors and transforming them into macrophages. These were then exposed to 24 different stimuli mimicking infection and inflammation, and the gene expression profiles assessed six and 24 hours later, to see which genes were turned on or off in response.