A mother-child segregation distortion for the Rh system. New evidence for another compatibility system associated with Rh

Abstract

In the maternity service of a private hospital in Santiago, Chile, 6,974 mother-infant pairs typed for the D-d alleles of the Rh system were collected. The segregation analysis, made by means of the T mother-child matrix assuming Hardy-Weinberg equilibrium, reveals that: Rh(-) mothers have a higher rate of admission than do Rh(+) mothers; Rh(+) mothers produce fewer Rh(-) infants than expected; and, with less significance, Rh(-) mothers produce more Rh(+) infants than expected. This leads to a reduction in the proportion of dd individuals from mothers to their children. The only plausible hypothesis to explain this finding is that selection is not related to the known Rh antigenic specificities. The reduction of the proportion of dd individuals in 1 generation leads us to review models on Rh polymorphism.