Complement Factor H Related 1

Complement factor H-related protein 1 (CFHR1) is a plasma protein of five short consensus repeat domains encoded within the CFH gene cluster at chromosome 1q32. Although homologous to factor H, CFHR1 lacks strong complement-regulatory activity and instead binds C3b and C4b and associates with circulating C-reactive protein, likely fine-tuning complement activation at inflammatory sites and on microbial surfaces. Homozygous deletion of CFHR1 and CFHR3, common in many populations, protects against typical hemolytic uremic syndrome but predisposes to anti-factor H autoantibody-mediated disease. Recombinant CFHR1 is used in genotyping-correlated functional and autoimmunity studies.