International Society of Blood Transfusion Working Party on Red Cell Immunogenetics and Blood Group Terminology Report of Gothenburg, Barcelona and four virtual business meetings: Update on blood group systems.

BACKGROUND AND

OBJECTIVES

The International Society of Blood Transfusion (ISBT) Working Party (WP) on Red Cell Immunogenetics and Blood Group Terminology (RCI&BGT) held six business meetings between December 2021 and June 2024. This report describes the new blood group systems and antigens ratified during these meetings.

MATERIALS AND

METHODS

Candidate systems and antigens were reviewed according to serological, genetic and biological evidence. This evidence was matched against defined criteria, and the acknowledged systems/antigens were assigned a unique identifier.

RESULTS

Four new systems, ER (ISBT 044), CD36 (ISBT 045), ATP11C (ISBT 046) and MAL (ISBT 047), were ratified. CD36 and ATP11C were de novo entries, while ER and MAL systems resolved the genetic basis for the Er and AnWj antigens. Thirteen antigens were added to existing systems: one each to LU (005), YT (011), SC (013), LW (016), KN (022), GLOB (028); an antithetical pair to KEL (006); two antigens to RHAG (030); and three to CTL2 (039). Two CTL2 antigens defined the hitherto unresolved antithetical antigens, Csa/Csb, whose genetic basis coincides with those of variants responsible for the HNA-3a/3b neutrophil antigens, respectively.

CONCLUSION

As of June 2024, the ISBT has acknowledged 47 blood group systems, comprising 366 antigens. The WP continues to ratify new systems and antigens, which are available on the ISBT website (http://www.isbtweb.org/working-parties/red-cell-immunogenetics-and-blood-group-terminology/).