Twinning and Blood Groups — I. ABO frequencies in twins and controls: immunological considerations

Abstract

Several studies have appeared in the literature to support the hypothesis of a differential incidence of twin births according to the antigenic structure of maternal erythrocytes (Gedda, 1961).Osborne and DeGeorge (1957) wrote that twin births exhibit a higher incidence when mothers belong to group O, as compared to other groups within the ABO system; a similarly increased incidence of twin births was indicated for rh-negative mothers within the Rh-Hr system.The availability of a large number of immunohematological data concerning twin pairs and nontwin individuals examined in our Institute have encouraged us to verify whether this material could reveal some a posteriori effect of the selective tendencies that have been related to the parental level.Limiting our study in this phase to the ABO system, we have collected data on 1190 twin individuals and 1454 nontwin individuals, for all of whom the ABO blood group had been recorded.The first step in our analysis was the perequation of the nontwin distribution to the twin distribution, obtaining the figures reported in the column “controls” in Tab. I.

Twinning and Blood Groups — II. Distribution of ABO, MN and Rh-Hr Phenotypes in a Twin Sample

“…Each such experimental distribution was matched against the corresponding expected distribution in three alternative hypotheses: a) expected distribution in the hypothesis of genetic equilibrium (Hardy-Weinberg) based on gene frequencies derived, by the maximum likelihood method, from each sample or subsample; b) expected distribution in the hypothesis that the non-twin control sample reported by Bolognesi and Milani-Comparetti (1970) would still be valid as representing the population from which our present twin sample was drawn; c) expected distribution in the hypothesis that pooling the three population samples reported by Mourant et al (1976) for the Rome area would better represent the population from which our twin sample was drawn. Tables 4, 5 and 6 list the results of these comparisons in terms of levels of significance (chi square).…”

“…This prompted us to undertake a series of studies on the subject. In a previous study (Bolognesi and Milani-Comparetti 1970) Acta Genet. Med.…”