Double Autosomal Trisomy and Mosaicism

There have been relatively few reports of individuals with double autosomal trisomy (Gagnon et al., 1961; Becker, Burke, and Albert, 1963; Hsu et al., 1965; Marks, Wiggins, and Spector, 1967). There have been rather more published accounts of individuals showing trisomy for one autosome and an additional chromosome in the sex chromosome complement as well. Of these, only those with the sex chromosome constitution XXX can properly be described as double trisomics (Uchida et al., 1962b; Day et al., 1963; Ricci and Borgatti, 1963; Yunis, Hook, and Alter, 1964; F. J. W. Lewis and L. Haas, 1965, personal communication; A. E. Mirkinson, 1966, personal communication), the others having the sex chromosome constitution XXY (Ford et al., 1959; Lanman et al., 1960; Lehmann and Forssman, 1960; Hustinx et al., 1961; R. A. Pfeiffer, 1964, personal communication), or less commonly XYY (Gustavson et al., 1962; Verresen and van den Berghe, 1965). With few exceptions, the reports of double aneuploidy have concerned individuals with only a single cell line. Hsu and her colleagues described a child who was a mosaic, with a normal cell line and a doubly trisomic line, trisomic for chromosomes 18 and 21. A cell line trisomic for chromosome 21 and a second line trisomic for chromosome 18 were demonstrated in a child reported by Marks et al. (1967). We earlier reported a child who was a mosaic for trisomy 13-15 and trisomy 17-18 (Baikie, Garson, and Birrell, 1965), and it is that case we now describe in detail.