Studies on Blood from the Original Rh(null) Proposita and Relatives

Abstract

A relative of the original Rh proposita, of group R(1)R(2), shows weak expression of his Rh antigens, and is thought to be an Rhnuii heterozygote. His wife and 3 of their 4 children show normal Rh antigen expression, but one daughter showed weak Rh antigen expression, as determined by quantitative haemagglutination. The observations support the proposition that the father is heterozygous for an unlinked modifier of Rh antigen expression. Stomatocytosis, observed in the Rh(null) proposita and other Rhnuii individuals, was also observed, but to a lesser degree, in the blood of an other individual thought to be an Rhnuii heterozygote. This observation also supports the earlier conclusion that the Rh(null) phenotype of the proposita is due to homozygosity for inactive alleles at a locus which controls the biosynthesis of precursor for Rh and LW antigens. Osmotic fragility tests showed that the Rhnuii cells were more fragile than cells with normal Rh antigen expression, and cells from Rhnuii heterozygotes had intermediate fragility. This is consistent with the proposition that Rh antigens are normal structural components of the red cell membrane, and the Rh(null) heterozygotes show a deficiency of the Rh antigenic structures.