Herein is reported a IgG FC region comprising a First polypeptide Variant FC region and a Second polypeptide Variant FC region,In which: a) the first polypeptide Variant FC region is derived from a First polypeptide FC region of IgG Class parent and the second polypeptide FC region is derived from a Second polypeptide FC region of IgG Class Parent, so that the first polypeptide FC region Parental IgG class is identical to or different from the second polypeptide IgG FC region.And (b) the first polypeptide Variant FC region differs from the second polypeptide Variant FC region in one or more amino acid residues of the amino acid residues in which the first polypeptide IgG FC region differs from the second parental polypeptide FC region IgG Class.And (c) The FC region of IgG Class that includes the first polypeptide Variant FC region and the second polypeptide Variant FC region have an affinity for the Human fc receptor which is different from that of the FC region of IgG Class that includes the first polypeptide IgG Class Stop NTAL (a) and the second polypeptide IgG FC region of parental)In the First region and the second polypeptide FC polypeptide FC region or both polypeptides include FC region independently of each other or combinations of Mutations: mutations t307h q311h E430 h, or, or, 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 E430, or m252y s254t t256e H and and and, and and and or n434h m252y s254t t256e,Or t307h and q311h and m252y and s254t and t256e, or t307h a
