FGF23 is produced primarily by osteoblasts and osteocytes; however, it can be pathologically upregulated in other disease states such as hypertrophic cardiomyopathy.4 Indeed it has been long argued that the increases in FGF23 are causal for cardiac hypertrophy,25 although via Klotho‐independent processes. The gene discussed is FGF23; the disease is hypertrophic cardiomyopathy.