EGFR and familial primary hypomagnesemia: First-line therapy in metastatic colorectal cancer consists in chemotherapy doublet by combining the above regimens with the anti-EGFR antibodies (in patients with wild-type RAS), or bevacizumab (in the case of mutated RAS), or in chemotherapy triplet (FOLFOXIRI: 5-Fluorouracil, leucovorin, irinotecan, and oxaliplatin) plus bevacizumab in case of BRAF mutation: hyponatremia, hypomagnesemia, hypocalcemia, hypokalemia, and hypophosphatemia are the ion disorders that these patients can experience (Tables 1, 6) (168).