Structural analysis. Positions of aHUS-associated mutations found in this study (D²⁵⁴ and K³²⁵), in relation to the MIDAS site (in ball and stick representation) and previously found mutations of F²⁶¹ and K²⁹⁸⁸  on the VWF-A domain of factor B. The aHUS-associated mutations described by Goicoechea de Jorge et al have been originally named according to the protein numbering with the leader peptide.⁸  For clarity in this work, the number of both previously described residues is given according to the protein structure: F286 is F261 here and K323 is K298 here.