As RAS activation is known to induce FGF23 and thus hypophosphatemia through diminishing phosphate reabsorption and increasing urinary phosphate excretion, treatment with the MEK inhibitor trametinib was started at a dosage of 0.025 mg/kg/day (0,25mg) in a hospital setting at the age of 26 months [24]. The gene discussed is FGF23; the disease is hypophosphatemia.