An update on the Chido/Rodgers blood group system

This update of the Chido/Rodgers blood group system (Mougey R. A review of the Chido/Rodgers blood group. Immunohematology 2010;26:30–8) summarizes the current understanding of the genetics and serology of this blood group (of which little has changed since the publication of the first review) in a table format as well as summarizes the gene frequencies and disease association with low copy number of C4A or C4B genes. The International Society of Blood Transfusion (ISBT) has designated the ISBT number 017 to this system and the abbreviation CH/RG for the antigen or antibody notation. There are currently nine antigens in the CH/RG system. A brief discussion on the serologic challenges of detecting the antibodies and of newer information on the disease associations is provided. This review concludes with some speculation on how our understanding of C4 genes may be illuminated by current investigation into complexities of autoimmunity and the role of C4 and its progression to a disease state.