Anti-FHR4 antibodies enable researchers to detect and measure the FHR4 antigen in biological samples. This target is a reported synonym of the CFHR4 gene, which encodes complement factor H related 4. This protein is known to be involved in complement regulation. The human version of FHR4 has a canonical amino acid length of 578 residues and a protein mass of 65.4 kilodaltons, although 3 isoforms have been identified. It is reported to be a secreted protein. Other names for this target antigen include CFHL4 and FHR-4.