In this example, the chain of causality between one drug and one disease was examined and inferred by domain experts who took advantage of the following knowledge in bexarotene-related pathways: (1) drug-target (e.g., bexarotene is an RXR agonist); (2) target involved pathway (e.g., LXR:RXR activation pathway); (3) transcriptional responses in a given pathway (e.g., increased ApoE gene expression in the LXR:RXR activation pathway); (4) genetic mechanism of disease (e.g., ApoE is associated with AD). Here, APOE is linked to Alzheimer disease.