Reproduction in Human Autosomal Trisomics

Abstract

Introduction At the present time the only examples of reproduction in human autosomal trisomics are the few confirmed cases of mongol females who have borne children of nonmongol fathers^1-15(Table 5). The unconfirmed or unpublished cases are, of course, difficult to evaluate and will be excluded from this discussion.^16-19There are examples of the reproductive behavior of other than human organisms with one autosome represented 3 times. In Drosophila the only known viable autosomal trisomic is the "triple-IV" fly with one extra chromosome in Pair IV. When these exceptional flies are crossed with chromosome normals, the distribution of genetic markers among the offspring is such as to indicate that 2 of the trisomie chromosomes move to one pole at meiosis and the third moves to the opposite pole, the expected frequency of the formation of a germ cell with one extra chromosome being 50%, as is the expected frequency of the