2009). We first investigate the ability of long‐term (2 weeks) or short‐term (2 days) ME‐1 administration to induce hypomagnesemia or hyperphosphatemia, and then we administer a single dose of ME‐1 to Mg2+‐deprived or control mice in order to investigate the involvement of EGFR in the Mg2+ conservation response triggered by dietary Mg2+ deprivation. The gene discussed is EGFR; the disease is familial primary hypomagnesemia.