AN INTERACTION BETWEEN ALLELES AT THE RH LOCUS IN MAN WHICH WEAKENS THE REACTIVITY OF THE RH 0 FACTOR (D u )

Abstract

Eleven families in which the Cde chromosome (r1 gene) was present and including 8 from a Roman-Jewish community, in which the frequency of the Cde chromosome was over 4%, were scored against at least 5 anti-D saline agglutinating sera which contained no other antibody. The total scores indicated that the reactivity of the D antigens produced by the same CDe chromosomes was affected by the presence of a cde or a Cde chromosome. When Rh-positive members of 4 families were titrated on 2 different days against the same 5 anti-D sera, an analysis of variance indicated that the 5 D/Cde genotypes showed a lower D reactivity than the 7 D/non-Cde genotypes. Four similar experiments gave the same results, testing a total of 19 certain D/Cde, 20 D/not-Cde and 4 D/? genotypes. It was concluded that when Cde was paired with a normal D chromosome, there was a significant weakening of D reactivity, and that this interaction between alleles at the Rh locus indicated that Rh was a complex locus.