– Complement factor H-related protein 4 is a protein that in humans is encoded by the CFHR4 gene. It is a secreted protein that belongs to the complement factor H protein family. Members of the H-related protein family are exclusively composed of individually folded protein domains. CFHR4 is synthesized as a 578 amino acid precursor that contains an 19 amino acid signal peptide and a 569 amino acid mature chain. Human CFHR4 is involved in complement regulation. It can associate with lipoproteins and may play a role in lipid metabolism.