SCN4A and hyperkalemic periodic paralysis: In hyperkalemic periodic paralysis (hyperPP), the attacks of flaccid muscular paralysis with high serum potassium levels last minutes to hours and can happen at any time of the day, often beginning in the first decade of life [16]. The mutation that causes this disorder is dominant on SCN4A, with linkage to the sodium channel expressed in muscle. Symptoms are frequently triggered by rest after exertion, low temperatures, or consumption of foods high in potassium.