AVPR2 and nephrogenic syndrome of inappropriate antidiuresis: In the protein sequence, the arginine residue at position 137 is of major significance since mutations may cause constitutive activation of V2R resulting in nephrogenic syndrome of inappropriate antidiuresis (N‐SIAD) or X‐linked nephrogenic diabetes insipidus (NDI) due to loss of function of the V2R (Feldman et al.