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 fathers1-15 (Table 5). The unconfirmed or unpublished cases are, of course, difficult to evaluate and will be excluded from this discussion.16-19 There are examples of the reproductive behavior of other than human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
PRIEST JH, THULINE HC, NORBY DE, LaVECK GD. Reproduction in Human Autosomal Trisomics: Chromosome Studies of a Mongol Mother, Her Nonmongol Twins, and Her Family. Am J Dis Child. 1963;105(1):31–41. doi:10.1001/archpedi.1963.02080040033006
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