Anti-factor c3 sac7d variants and their medical use for treating complement-mediated disorders

A polypeptide comprising a variant of a member of a Sac7d family binding to C3 and/or to C3b, wherein the variant comprises from 4 to 20 mutated residues in an interface of binding of the member of the Sac7d family to its natural ligand, and wherein the variant comprises W24Y and R42W mutations with numbering corresponding to numbering of Sac7d residues as depicted in SEQ ID NO:

• 1.