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 investigate a possible association between ELO and the gene controlling Diego blood group polymorphisms, we undertook molecular studies of AE1 (anion exchanger 1 gene).
Materials and methods: DNA from a family segregating 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 sequencing were conducted.
Results: We have observed an exon 12 SSCP in all ELO+ individuals tested. This SSCP is the result of a C-->T mutation in exon 12 of AE1 which leads to an Arg432-->Trp amino acid substitution in the putative first extracellular loop of band 3 and thereby accounts for the Diego blood group system polymorphism known as ELO.
Conclusions: In light of these findings, the International Society of Blood Transfusion Working Party on Terminology for Red Cell Surface Antigens has designated ELO as a member of the Diego blood group system (010008 or D18) and rendered the previous numerical designation (700.51) obsolete.