Investigations into the Identification and Characterisation of Novel Blood Groups.pdf

Abstract

Blood group antigens are inherited traits present on erythrocyte membranes and other tissues, that are defined by alloantibodies. These are immune antibodies produced in response to exposure to incompatible red blood cell antigens through pregnancy, transfusion, or transplantation. Additionally, some antibodies to blood groups, such as those in the ABO system, are naturally occurring due to the presence of similar antigens on common environmental substances like bacteria and food. To date, there are 362 authenticated blood group antigens classified in 45 human blood group systems that have been recognized by the International Society of Blood Transfusion (ISBT). However, the molecular background of some antigens remains uncharacterized. These uncharacterized antigens, whose molecular basis is yet to be determined, may either define a new antigen within an existing system or constitute a novel blood group system. The research in this thesis focused on investigating uncharacterized and unmapped erythrocyte antigens. We utilized the International Blood Group Reference Laboratory (IBGRL) archived rare sera and red cell samples for this purpose. We employed a genomic approach, utilizing whole exome sequencing and followed by Sanger sequencing to identify the genetic alterations responsible for these antigens. In vitro expression studies, including both CRISPR Cas9 knock-out and over-expression of genes of interest were conducted to confirm the molecular basis. This work revealed that PIEZO1 is responsible for the expression of the Er antigens (Era, Erb, Er3, Er4, Er5), establishing the Er blood group system. Furthermore, we identified MAL as the gene responsible for the expression of the AnWj high prevalence antigen and establishing a further blood group system. We also identified and characterised a novel high prevalence antigen, subsequently assigned to the Lutheran blood group system (LUOM).