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-C^w and anti-C^x The Rh antigens C^w (RH8) and, more strikingly, C^x (RH9) have each an exceptionally high frequency in Finns. Our studies on their genetic relationship indicate that the three antigens C^w C^x 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.

Rh and RHAG Blood Group Systems

“…Anti -MAR was found in a Finnish woman whose red cells were C w + C x + D + C + c − E − e + and who was probably heterozygous DCC w e/DCC x e [388] . Testing of 10 045 Finnish donors revealed 21 MAR -negatives: nine were C w + C x − (probably RHCE * C w /C w ), three were C w − C x + (RHCE * C x /C x ), and nine were C w + C x + ( RHCE * C w /C x ).…”

“…antigen MAR [388] . C w and C x result from single nucleotide changes in exon 1 of RHCE (usually RHCE * Ce ) encoding amino acid substitutions in the fi rst extracellular loop: 122A > G, Gln41Arg in C w ; 106G > A, Ala36Thr in C x [389] .…”

Blood Group Terminology 1995: ISBT Working Party on Terminology for Red Cell Surface Antigens

“…Family information (lod score = 4.12 at 8 = 0) was also responsible for the elevation of 700048 (FPTT) to RH50, an antigen associated with unusual DCe and Dce (with RH33) complexes, and, in some examples, with a partial RHl (D) antigen (DFR) [56, 571. The high incidence antigen RH51 (MAR) has an antithetical relationship with RH8 (C") and RH9 (C") (lod score = 10.76 at 0 = 0) [58].…”