Insulin acts synergistically with thyroid hormone to drive potassium into the cell; hence, attacks are often precipitated by a heavy meal, and hyperinsulinemia is a common laboratory finding during the acute episode [6,7]. Advances in understanding the pathophysiology of TPP have identified mutations in the inwardly rectifying potassium channel Kir 2.6. Loss-of-function mutations in the genes encoding these channels (Kir2.6) can prevent the flow of potassium out of skeletal muscle cells, disrupting potassium homeostasis [7,13,14]. Here, KCNJ18 is linked to hyperinsulinism.