FGF23 and hydrops fetalis: Finally, transverse aortic constriction (TAC) was performed in adult wild-type mice, double Fgf23/VDR (fibroblast growth factor-23/vitamin D receptor) mutants, and VDR-deficient mice to investigate bone changes in an HF model caused by afterload-induced cardiac hypertrophy, 4 and 6 weeks after TAC.