MAR, a Novel High‐Incidence Rh Antigen Revealing the Existence of an Allelic Sub‐System Including C^w (Rh8) and C^x (Rh9) with Exceptional Distribution in the Finnish Population

Abstract

We present new genetic evidence obtained from population studies on Finns and from the studies on Finnish blood donors as well as their selected families using an antibody that defines a novel high-incidence Rh antigen MAR. Anti-MAR antibody shows an antithetical relationship to both anti-Cw and anti-Cx. The Rh antigens Cw (RH8) and, more strikingly, Cx (RH9) have each an exceptionally high frequency in Finns. Our studies on their genetic relationship indicate that the three antigens Cw, Cx and MAR behave as if being determined by alleles of the same Rh sub-system. Furthermore, we conclude that this sub-system manifests an inheritance pattern that is distinct from but analogous to that of the two well-known allelic sub-systems of C/c and E/e antigens.

A MAR‐like antibody in a DCWe/DCWe person

“…Additional testing was performed on samples from the case reported in 1983, and the results are included here. The specificity of the antibody made by our patient, CJ, is slightly different from that of the antibodies previously reported, which were made by two MAR– persons 1,2 . Evidence is provided to indicate that examples of “anti‐MAR” differ slightly, depending upon the C W /C X status of the antibody maker.…”

“…We report here the first example of an antibody, directed at a high‐incidence Rh antigen, made by a patient with DC W e/DC W e MAR‐negative RBCs. The specificity of the antibody appears to be related to anti‐MAR (anti‐RH51), which was produced by a patient with the rare DC W e/DC X e phenotype 1 . An antibody with similar specificity was made by a DC X e/DC X e female patient and reported in an abstract in 1983 2 .…”

“…Her antibody does not react with RBCs with a double dose of C X or C W antigens, nor with RBCs expressing C W and C X in trans (Table 1). Sistonen et al 1 reported that 21 RBC samples (9 were C W +C X –, 9 were C W +C X +, and 3 were C W –C X +) were tested with her serum and found compatible. This large number of available MAR‐negative RBC samples is due to the exceptionally high incidence of C W and C X in the Finnish population 1 …”

“…The MAR antigen is also missing from RBCs with the Rh deletion phenotypes: Rh null , D––, Dc–, and DC W –. The original report of the MAR antigen 1 describes anti‐MAR in the serum of a DC W e/DC X e Finnish woman. This patient had never received a transfusion, and her serum contained anti‐Fy a and anti‐M in addition to anti‐MAR.…”

The Impact of Using Genotyped Reagent Red Blood Cells in Antibody Identification

“…Only individuals who are combined heterozygous for RhC w and C x (RhC w C x ) or homozygous for RhC w or RhC x , or who are Rh null or RhD-, are MAR-(like)-negative. The original MAR-negative individual (RhC w C x ) was found in Finland [13]. Our studies revealed that in our donor population in Southwestern Germany only one of 19,000 blood donors is MAR-negative.…”