Previous observational data suggested that VDRAs were associated with a benefit on mortality in end-stage kidney failure [39], but caution has been raised in the CKD Stage 3-4 subgroup due to adverse outcomes, particularly hypercalcaemia and augmentation of fibroblast growth factor 23 (FGF23) levels, as reviewed recently [35]. The gene discussed is FGF23; the disease is chronic kidney disease.