A Weak Example of the Blood Group Antigen A

Abstract

Summary A weak form of the antigen A is reported in a healthy adult. It does not appear to correspond with any other weak form of A previously reported, except perhaps with that of Weiner, Race and Sanger. Centrifugation methods with antisera from donors injected with group specific substances are essential for the reliable demonstration of this antigen which, under these circumstances, gives a typical microscopic picture of isolated small clumps of cells set in a sea of unagglutinated cells. No symbol is used to designate this phenotype as its position within the ABO system is not clear. Résumé Les auteurs décrivent un antigène A faible chez un adulte en bonne santé. Il ne semble pas correspondre aux autres formes de A faibles déjà décrites sinon à celles de Weiner, Race et Sanger. Les méthodes de centrifugation avec des antisérums provenant de donneurs immunisés avec des substances de groupes spécifiques sont indispensables pour la mise en évidence de cet antigène qui, dans ces conditions, donne l'image microscopique typique de quelques petites agglutinations érythrocytaires isolées parmi un grand nombre d'érythrocytes non agglutinés. Il n'y a pas de symbole pour désigner ce phénotype et sa position dans le système ABO est peu claire. Zusammenfassung Bei einem gesunden Erwachsenen wurde eine schwache A‐Eigen‐schaft gefunden, welche, mit Ausnahme derjenigen von Weiner, Race und Sanger, mit keiner bisher beschriebenen schwachen A‐Variante übereinstimmt. Der Nachweis erfolgt am besten mit einer Zentrifugiertechnik unter Verwendung von Antiseren von Spendern, welche mit gruppenspezifischen Substanzen immunisiert worden sind. Mit dieser Technik ergibt sich ein charakteristisches Agglutinationsbild mit isolierten kleinen Agglutinaten in einem See von unagglutinierten Zellen. Da die Stellung dieses Antigens im ABO‐Blutgruppensystem noch unklar ist, wurde verzichtet, diesen Phänotyp mit einem neuen Symbol zu bezeichnen.

An Inherited Blood Group A Variant in the Finnish Population

“…The Annn variant, however, has not been found to differ in a substantial way from published descriptions of the phenotype Aend [12,20,21,30].…”

An Inherited Blood Group A Variant in the Finnish Population

“…The Afmn variant, however, has not been found to differ in a substantial way from published descriptions of the phenotype Aend [12,20,21,30,31], Originally stated to be nonagglutinable by anti-A or anti-A + B sera in the tube sedimentation technique, group Aend cells were later found to form microscopically demonstrable agglutinates with immune anti-A or anti-A + B sera from stimulated donors, if a tube centrifugation procedure was used. Group Aend persons secrete H but not A substance, as do the Finnish group A variant cases, and anti-Aj agglutinins are present in their sera.…”

Notations for Two Weak A Variants: A(end) and A(el)

“…Moore et al [3,4] reported two similar and probably identical phe notypes in 1961 ; Jacobowicz et al [2] found a further example in 1963. Now that four examples have been reported, in two of which [4,9] the variant was shown to be inherited, to leave this phenotype unnamed is to invite confusion.…”

“…The use of letters for such variants was suggested by Weiner et al [9] ; the letters themselves are derived from the propositus' name in the first report [9]. The serological characteristics of this phenotype are briefly thus: 1. a) Using a sedimentation technique, no reactions are given by anti-A from donors who have not been injected with group specific substance [3,9]. b) Using the same technique, a variable proportion of anti-A from "stimulated donors" produce very weak agglutination [4].…”

“…c) Using a centrifugation technique and anti-A or anti-A+B from "stimulated" donors, the majority of the tests show very weak agglutination [3,4]. d) The agglutination produced is distinctive: from 0.5-1% of the cells form small clusters in a sea of unagglutinated cells [3,9].…”