THE ELO BLOOD-GROUP POLYMORPHISM IS LOCATED IN THE PUTATIVE FIRST EXTRACELLULAR LOOP OF HUMAN ERYTHROCYTE BAND-3

Background and Objectives: The low incidence red cell antigen ELO (700 .51) has been excluded from 13 of 23 established blood group systems. Information relative to the Diego system has not been reported. To inv estigate a possible association between ELO and the gene controlling D iego blood group polymorphisms, we undertook molecular studies of AE1 (anion exchanger 1 gene). Materials and Methods: DNA from a family seg regating for ELO and from the original ELO proposita was amplified by PCR using intronic primers flanking exons 11-20 of AE1. Subsequently, single-strand conformational polymorphism (SSCP) analysis and DNA sequ encing were conducted. Results: We have observed an exon 12 SSCP in al l ELO+ individuals tested. This SSCP is the result of a C --> T mutati on in exon 12 of AE1 which leads to an Arg(432) --> Trp amino acid sub stitution in the putative first extracellular loop of band 3 and there by accounts for the Diego blood group system polymorphism known as ELO . Conclusions: In light of these findings, the International Society o f Blood Transfusion Working Party on Terminology for Red Cell Surface Antigens has designated ELO as a member of the Diego blood group syste m (010008 or DI8) and rendered the previous numerical designation (700 .51) obsolete.