Complement component 4

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complement component 4A (Rodgers blood group)
Symbol C4A
Entrez 720
HUGO 1323
OMIM 120810
RefSeq NM_007293
UniProt P0C0L4
Other data
Locus Chr. 6 p21.3
complement component 4B (Chido blood group)
Symbol C4B
Entrez 721
HUGO 1324
OMIM 120820
RefSeq NM_000592
UniProt P0C0L5
Other data
Locus Chr. 6 p21.3

Complement component 4 is a protein involved in the complement system.

It is cleaved into proteins 4a and 4b; 4b can be further cleaved into 4c and 4d.[1]

Classical pathway. (Some labels are in Polish.)

Clinical significance[edit]

It is responsible for the Chido Rodgers blood group system.[2]

C4d has been identified as a biomarker for systemic lupus erythematosus.[3]


  1. ^
  2. ^ Chido Rodgers blood group system at BGMUT Blood Group Antigen Gene Mutation Database at NCBI, NIH
  3. ^ Liu CC, Manzi S, Kao AH, Navratil JS, Ruffing MJ, Ahearn JM (2005). "Reticulocytes bearing C4d as biomarkers of disease activity for systemic lupus erythematosus". Arthritis Rheum. 52 (10): 3087–99. doi:10.1002/art.21305. PMID 16200588.