AQP2 and Schnyder corneal dystrophy: In summary, in contrast to the low levels of circulatory vasopressin and expression of AQP2 and NKCC2 in central diabetes insipidus and high levels of circulatory vasopressin and low levels of expression of AQP2, UTA1, and NKCC2 caused by nephrogenic diabetes insipidus, SCD‐induced urinary concentration defect is associated with elevated urinary vasopressin level and increased abundance of AQP2, UTA1, ENaC‐β subunit and possible NKCC2 protein and apical targeting of AQP2 in the mouse medulla.