As used herein, an IgG family 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 family Fc-region polypeptide , The second variant Fc-region polypeptide is derived from a second maternal IgG family Fc-region polypeptide, whereby the first maternal IgG family Fc-region polypeptide is homologous or different from the second maternal IgG family Fc-region polypeptide, and b) The first variant Fc-region polypeptide is different from the second variant Fc-region polypeptide in one or more amino acid residues in addition to the amino acid residue differing from the second parent IgG family Fc-region polypeptide, c) an IgG family Fc-region comprising a first variant Fc-region polypeptide and a second variant Fc-region polypeptide comprises a first mature IgG family of a) Domain polypeptide and an affinity for a human Fc-receptor that is different from that of an IgG family Fc-region comprising a second IgG family Fc-region polypeptide of a), wherein the first Fc-region polypeptide or the second Fc One of the following mutations or mutant combinations: either T307H or Q311H, or E430H, 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 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, 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 E430H and M252Y and S254T and T256E or N434H and M252Y and S254T and T256E or T307H and Q311H and M252Y and S254T and T256E or T307H and E430H and M252Y And S254T and T256E or T307H and N434A and M252Y and S254T and T256
