KCNN4 and Schnyder corneal dystrophy: Three major ion transport pathways are involved in sickle cell dehydration: the K‐Cl cotransporters (KCCs), the Gardos channel (KCNN4), and Psickle, the deoxyhemoglobin S polymerization‐induced cation permeability found only in red cells of SCD patients, and most likely mediated by PIEZO1.9