MNSs Frequencies in 3,895 Swiss Blood Donors

Abstract. In a series of MNSs tests on 3,895 Swiss blood donors, in which use was made of the dosage effect of anti‐M and anti‐N sera for distinguishing rare heterozygotes within groups M and N, 19 phenotypes were recognized. Ten of these were rare, involving only 15 persons, and the corresponding genotypes were ascertained. The frequencies of the alleles thus recognized at the MN and the Ss locus were obtained by counting. The number of possible combinations of these ‘single genes’ to gene complexes is 15, and 10 of them occurred in the series. The frequencies of these complexes were estimated by computer. The genotype proportions expected from the gene and gene complex frequencies were shown to agree closely with the observed proportions. The possibility that, owing to the special methods employed, certain very rare genotypes escaped detection is discussed.