A "new" low-incidence red cell antigen, LOCR, associated with altered expression of Rh antigens.
BACKGROUND
Mild cases of hemolytic disease of the newborn were being studied when it was recognized that the propositi's red cells carried a novel antigen.


METHODS
Serologic and genetic studies of a new low-incidence antigen, LOCR (International Society of Blood Transfusion series number 700.53), were performed.


RESULTS
The antigen is associated with altered expression of the Rh antigen c in two unrelated families and in a third proposita and with an altered expression of e in a fourth proposita. The lods for the gene controlling LOCR relative to Rh are 2.107 at theta = 0.00; that is, they fall short of the requirement for inclusion of the antigen in the Rh blood group system. LOCR is excluded from the ABO, MNS, Lutheran, Kell, Duffy, Kidd, Xg, Chido/Rodgers, Kx, and Gerbich blood group systems. Genetic evidence suggests it is not part of the Yt, Colton, or LW systems.


CONCLUSIONS
Serologic evidence that LOCR is associated with altered expression of c or e strongly suggests that LOCR is part of the Rh blood group system. However, the genetic evidence falls short of the level required for system assignment.
Rh Laboratory, University of Manitoba, Winnipeg, Canada.
G
G
Coghlan
J
J
McCreary
V
V
Underwood
T
T
Zelinski
D000941:Antigens / Q000097:blood* / Q000235:genetics; D001789:Blood Group Antigens / Q000276:immunology; D004899:Erythroblastosis, Fetal / Q000235:genetics / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology*; D015870:Gene Expression; D006801:Humans; D007231:Infant, Newborn; D007518:Isoantibodies / Q000097:blood; D007519:Isoantigens / Q000235:genetics* / Q000276:immunology; D010375:Pedigree; D012204:Rh-Hr Blood-Group System / Q000235:genetics*
D000941:Antigens; D001789:Blood Group Antigens; D007518:Isoantibodies; D007519:Isoantigens; C088061:LOCR, red cell antigen; D012204:Rh-Hr Blood-Group System