Plasma levels of elafin increase at the onset of skin aGvHD [23]; regenerating islet-derived protein 3α (REG3A), cytokeratin 18 (CK18), and hepatocyte growth factor levels are significantly higher in patients with lower GI acute GVHD compared to patients suffering from non-GvHD diarrhea [24, 25], these last three biomarkers increase in patients with liver aGvHD; however, they do not distinguish other potential causes of hyperbilirubinemia [26]. The gene discussed is KRT18; the disease is graft versus host disease.