MNSs Genetic Polymorphism and Intrauterine Selection Through Habitual Abortion

Distribution of MNSs genotypes and possible relation with gestational duration of aborted fetuses were studied in 88 couples with habitual abortion. An excess of couples S females X s males with respect to expected values assuming random mating was observed. The duration of gestation of aborted fetuses showed a negative linear relation with maternal doses of s and a positive linear relation with paternal dose of s. Mean gestational duration revealed a significant heterogeneity in relation to MN and Ss types of mating. A striking increase of mean gestational duration of aborted fetuses was observed in couples mother S x father s. Sialoglycoproteins similar to glycophorins controlled by MNSs system may be present at trophoblastic level and their genetic variability may contribute to modulation of maternal fetal immunological relationship. On the basis of recent studies suggesting that MNSs system may be an important determinant of graft-versus host disease and that HLA restricted proliferative responses occurs in vitro in association with M and N antigens, the possibility of maternal-fetal incompatibility in this system should be also considered.