Klotho is a bona fide longevity gene that, if inactivated, generates a phenotype identical to that of FGF23-null mice [36], characterized by premature aging, decreased lifespan, elevated 25(OH)D, hyperphosphatemia, ectopic calcification, skin and muscle atrophy, osteoporosis, and hearing loss. Here, KL is linked to hyperphosphatemia.