Furthermore, by comparing mice with targeted disruption of the PTH or 1α(OH)ase genes with PTH-1α(OH)ase double null mice, we found that PTH−/−1α(OH)ase−/− mice died of tetany with severe hypocalcemia by 3 weeks of age with severe defects in skeletal development [22]. This evidence concerns the gene PTH and Hypocalcemia.