While in some cases PheWAS highlighted associations with particular clinical endpoints, for example, the rediscovery of already known indications or biological pathways, such as the associations of type 2 diabetes with variants in NDUFA13 or the association of Alzheimer’s Disease with APOE, further research is needed to evaluate the causal role of the target in the corresponding disease and the beneficial or detrimental effects of modulating those targets pharmacologically. The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.