STK39 and Hyperkalemia: Along with WNK4, WNK1 regulates numerous ion channels involved in sodium and potassium transport in the kidney and in various other epithelia.7–10 Mutations in WNK1 are at the origin of pseudohypoaldosteronism type II (Gordon syndrome), characterized by hypertension and hyperkalemia.17 The role of the WNK-SPAK-NKCC2/NCC pathway is further highlighted by knockout mice models.