Estimation of Gene Frequencies in the MN System

Abstract

Negro and Caucasian samples typed with anti-M, N, S, s, M(1), Ua, Hu, He, Sj, and Tm indicate at least 14 and perhaps more than 26 alleles at the MNS locus, for which a notation is proposed. Gene frequencies arc estimated by maximum likelihood, using the Alltype computer program. The methodology, uses, and limitations of such estimates are discussed. There is a clear distinction between idiomorphs (with frequencies less than 0.01), many alternative sets of which can account for the rare phenotypes with or without typing errors, and polymorphs (alleles with frequencies between 0.01 and 0.99) which cannot fail to be recognized in a large sample. Idiomorphs require confirmatory family studies.

Sj, a New Antigen in the MN System, and Further Studies on Tm1

“…From the results of typing tests on a large series of Caucasian and Negro bloods the frequencies given in Table VI can be calculated. Because so many samples have been tested with so many sera the results herein have been subjected t o computer analysis by Dr. NEWTON MORTON and the estimated gene frequencies of the many genes in the MN system are presented by him in a separate paper [7] accompanying this publication. Further detailed discussion of the gene frequencies here is therefore unnecessary.…”

The estimation of blood group gene frequencies: a note on the allocation method

“…However, it should be noted that the estimation of gene frequencies for rare recessive alleles is uncertain when there is no proof that they are present in the sample. Similarly, uncertain estimates are obtained when some phenotypes represent many possible genotypes and the knowledge is incomplete regarding which allelic combinations of blood group factors are present in the population (Morton & Miki, 1968). To be able to judge whether a certain postulated rare allele should or should not be included in the estimation, it is useful to compare the goodness of fit to Hardy-Weinberg proportions obtained from gene frequency estimates including and not including the postulated allele.…”

Estimation of haplotype frequencies

“…Simple approximations to maximum Likelihood are inefficient and can give negative estimates (Mattiuz et al 1970). The principle of maximum likelihood provides good estimates of haplotype frequencies for most genetic systems (Morton & Miki 1968). However, a5 the number of distinguishable haplotypes becomes large, two difficulties are encountered.…”