The Phenotypes En(a−), Wr(a−b−), and En(a+), Wr(a+b−), and Further Studies on the Wright and En Blood Group Systems

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Abstract
In 1975, we showed18,19 an En(a–) blood sample to be phenotypically Wr(a−b−). In the current report, we describe tests that show that three En(a–) members of a single family, not believed to be related to the family of the previously tested En(a–) person, are also Wr(a−b−). They have red blood cells that neither react with nor adsorb anti-Wra or anti-Wrb. In addition, we have shown that the red blood cells of six EnaEn heterozygotes, in the family tested, are Wr(a−b+) but carry only a single dose of Wrb antigen. Tests on anti-Ena have shown conclusively that one example is a mixture of separable anti-Ena and anti-Wrb and that a second example may well contain the same two antibodies. By various methods, we have demonstrated that the red blood cells of the only known Wr(a + b–) individual are En(a+) and do not display any of the physicochemical abberations of the En(a–) phenotype. It is further shown that neuraminidase and trypsin do not denature the Wra or Wrb antigens in vitro, but that the protease ficin does have a limited ability to denature Wrb. Additional observations on the first reported1 example of anti-Wrb are included. These various findings have been considered in the light of gene linkage of, or gene interaction between, the En and Wright system genes. It is concluded that the evidence does not exclude the possibility that En is a silent allele at the WraWrb locus so that the genotype EnEn (or WrWr) might result in the phenotype En(a –), Wr(a –b –). However, it is also pointed out that the evidence equally well supports the postulation that the Wra and Wrb genes are unable to function in the absence of an Ena gene. If this latter theory is proved correct, the interaction between Ena and the Wright genes can be thought of as similar to that between the H and ABO, 23 or X'r and CDE genes.24 It is pointed out that if En is a silent allele at the MN locus (current evidence on this point is not conclusive.6,8,9) En and Wr cannot be synonymous for it is known that the Wra and M and N genes segregate independently.2,13,21,35 Location of En at the MN locus would not, however, refute the theory that Wra and Wrb cannot function in the absence of En. Finally, it is pointed out that the supposed anti-Wrb is probably just what its name implies but that even if this assumption is later disproved, the high incidence antigen defined by the antibody presently called anti-Wrb is unequivocally associated with Ena.