Document Type



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. Sialoglycopro- teins 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.