Hemolytic uremic syndrome (HUS) is a disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Recent studies have identified a factor H–associated form of HUS, caused by gene mutations that cluster in the C-terminal region of the complement regulator factor H. Here we report how three mutations (E1172Stop, R1210C, and R1215G; each of the latter two identified in three independent cases from different, unrelated families) affect protein function. All three mutations cause reduced binding to the central complement component C3b/C3d to heparin, as well as to endothelial cells. These defective features of the mutant factor H proteins explain progression of endothelial cell and microvascular damage in factor H–associated genetic HUS and indicate a protective role of factor H for tissue integrity during thrombus formation.
Tamara Manuelian, Jens Hellwage, Seppo Meri, Jessica Caprioli, Marina Noris, Stefan Heinen, Mihaly Jozsi, Hartmut P.H. Neumann, Giuseppe Remuzzi, Peter F. Zipfel
Binding of recombinant factor H and mutant factor H proteins to HUVECs