OSR1 and Hypokalemia: By opposition, Wnk4D561/+ mice bearing a OSR1 inactivation in the nephron (Wnk4D561/+:KSP-Osr1−/−) still display a complete FHHt phenotype16, even though OSR1 deficiency in the nephron causes hypokalemia under normal diet and systolic hypotension when mice are fed a low Na+ diet17.