Anti-Emm, a rare specificity to the high-incidence antigen Emm in an Indian patient defining the new blood group system EMM (ISBT042)

Abstract

A transfusion recipient lacking a high-incidence antigen (HIA) and has corresponding alloantibody pose a problem in providing compatible blood unit. We encountered a patient with an antibody to an HIA that required identification to assess if compatible blood could be organized. A 65-year-old male was posted for coronary artery bypass grafting surgery. His blood specimen collected in EDTA was referred to the blood bank to provide blood for transfusion. The patient, grouped AB RhD+, had an antibody reacting in saline and antiglobulin phases. It agglutinated all the red blood cells (RBCs) of the 11-cell panel and random donors, indicating specificity to an HIA, though one of his siblings was compatible. After ruling out specificity to HIAs such as H, Inb, and INRA (IN5), the specimen was referred to the New York Blood Centre for further work-up. The antibody reacted with examples of red cells lacking HIA, except those with the Emm− phenotype. The patient's RBCs were typed as Emm−. Anti-Emm in the patient appeared to be naturally occurring as there was no history of transfusion. Naturally occurring alloantibody to an HIA, identified as anti-Emm in phenotype Emm−, is rare and the first of its kind to be reported from India. The case was instrumental in recognizing the Emm as the new blood group system assigned with the symbol ISBT042.

Rare blood group registry in India-current challenges and future perspectives

“…The rare blood group phenotypes encountered in each country may vary according to the differences in ethnicity. Over a period of time, Bombay/para-Bombay,—D −/− D -, In (a+b-), Co (a-b-), I-i-, CdE/CdE, Mg, P-null and Emm are some of the rare blood group phenotypes that are reported in India ( Joshi and Vasantha, 2012 ; Shastry et al, 2020 ; Shah et al, 2021 ). Bombay phenotype is the most requested rare blood group in India ( Talukder et al, 2014 ).…”

Amelioration in cross-matching policy with subtypes of A for priority-based demand

“…However, in the clinical sector of human blood, there are 42 types of blood groups: A, B, O, Rh, Duffy, etc., (Dean, 2005). Recently, An Indian with the first EMM-negative blood type was identified during the preliminary procedure for cardiac surgery (Shah et al, 2021).…”