A Third Canadian Family with the Rh Chromosome D–

Abstract

A Canadian family of British descent has been found among whose m?mbers 17 heterozygous examples of the rare Rh chromosome D– were detected in addition to the homozygous D–/D– propositus. The parents of the propositus were first cousins.

The Rh ‘Deletion’ Phenotyp es and the Information they Provide about the Rh Genes

“…The propositus, a child of half second cousins, was presumed to be homo zygous for a very rare gene complex which was given the descriptive symbol D--/D--1.The identification of a further sixteen propositi considered homo zygous for genetic conditions leading to the absence of some, or all, of the expected Rh antigens have since been described [1,4,5,6,7, 9,13,15,18,20,25,26,27,28,29,32,34], the phenotypes being given the symbols D-/D-, DCW-/DCW-, Dc-/Dc-and -/-and being re ferred to, collectively, as Rh "deletion" phenotypes.The recognition of seventeen propositi, which has led to pedigree studies showing the apparently simple genetical inheritance of gene combinations leading to Rh phenotypes lacking any detectable form of the antithetical red blood cell antigens of the C and/or E series, also leads us to ask why the phenotypes -C-/-C-and -E/-E2 have not been detected.Perhaps cells are grouped D--/D-because rare antigens of the C and E series, for which antibodies are not known, are present. The -C-/-C-and --E/--E phenotypes might not lead to situations which would bring persons with them to notice; the phenotypes might not be identifiable even if persons with them were brought to notice, or 1 In the original publication the symbol -D-/-D-was used.…”