The primary objective is to show that the contribution of Klotho by the renal graft is an independent determinant of the evolution of the recipient's central arterial stiffness during the first year of renal transplant. The contribution of Klotho by the graft will be estimated by: its circulating concentrations assay, its urinary excretion assay, and, indirectly, by the circulating concentrations of FGF23. The recipient's central arterial stiffness will be estimated by the measure of the carotid-femoral pulse wave velocity, noninvasive reference method for measuring aortic stiffness in human.