Herein is reported an IgG class Fc-region comprising a first variant Fc-region polypeptide and a second variant Fc-region polypeptide, wherein a) the first variant Fc-region polypeptide is derived from a first parent IgG class Fc-region polypeptide and the second variant Fc-region polypeptide is derived from a second parent IgG class Fc-region polypeptide, whereby the first parent IgG class Fc- region polypeptide is identical to or different from the second parent IgG class Fc- region polypeptide, and b) the first variant Fc-region polypeptide differs from the second variant Fc-region polypeptide in one or more amino acid residues other than those amino acid residues in which the first parent IgG class Fc-region polypeptide differs from the second parent IgG class Fc-region polypeptide, and c) the Ig G class Fc-region comprising the first variant Fc-region polypeptide and the second variant Fc-region polypeptide has an affinity to a human Fc-receptor that is different than that of an IgG class Fc-region comprising the first parent IgG class Fc-region polypeptide of a) and the second parent IgG class Fc-region polypeptide of a), wherein either the first Fc-region polypeptide or the second Fc-region polypeptide or both Fc-region polypeptides comprise independently of each other one of the following mutations or combination of mutations: T307H, or Q311H, or E430 H, or N434H, or T307H and Q311H, or T307H and E430H, or T307H and N434A, or T307H and N434H, or T307Q and Q311H, or T307Q and E430H, or T307Q and N434H, or T307H and Q311H and E430H and N434A, or T307H and Q311H and E430H and N434H, or T307H and Q311H and E430H and N434Y, or T307Q and Q311H and E430H and N434A, or T307Q and Q311H and E430H and N434H, or T307Q and Q311H and E430H and N434Y, or T307Q and V308P and N434Y and Y436H, or T307H and M252Y and S254T and T256E, or T307Q and M252Y and S254T and T256E, or Q311H and M252Y and S254T and T256E, or E430 H and M252Y and S254T and T256E, or N434H and M252Y and S
