Studies on Blood from the Original RhnullProposita and Relatives

Abstract

A relative of the original Rh proposita, of group R1R2, shows weak expression of his Rh antigens, and is probably an Rhnull heterozygote. His wife and 3 of their 4 children show normal Rh antigen expression, but 1 daughter showed weak Rh antigen expression, as determined by quantitative hemagglutination. The father is apparently heterozygous for an unlinked modifier of Rh antigen expression. Stomatocytosis, observed in the Rhnull proposita and other Rhnull individuals, was also observed but to a lesser degree, in the blood of another individual thought to be an Rhnull heterozygote. The Rhnull phenotype of the proposita is apparently 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 Rhnull cells were more fragile than cells with normal Rh antigen expression, and cells from Rhnull heterozygotes had intermediate fragility. Rh antigens are apparently normal structural components of the red cell membrane. The Rhnull heterozygotes may show a deficiency of the Rh antigenic structures.