Fibroblast growth factor 23 was not clearly associated with kidney function or CKD (Figures 2, 3A,B and Supplementary Figures 3, 4A,B), although associations have been seen in some (Larsson et al., 2003; Fliser et al., 2007) but not all studies (Levin et al., 2014; Alderson et al., 2016). This evidence concerns the gene FGF23 and chronic kidney disease.