Familial C/G Translocation Causing Mitotic Nondisjunction

Cytogenetic studies in a patient with a de novo t(Cq-;Gp+).

“…The de novo occurrence of the t(Cq-;Gp+) chromosome in the phenotypically physically normal proposita contrasts with the 10 previously reported cases of similar translocations which were all inherited and were ascertained through children with congenital abnormalities (Yanagisawa, 1968;Pfeiffer, Laermann, and Heidtmann, 1967;Mikkelsen et al, 1968;Gray et al, 1966a;Gray, Dartnall, and Macnamara, 1966b;Lord, Casey, and Laurance, 1967;Weiss and Wolf, 1968). The varying phenotypes in these cases may result from involvement of different chromosomes of the C and G groups as well as duplication or deficiencies of different parts of these chromosomes.…”

Familial chromosomal mosaicism, genetic aspects

“…They postulated a genetic predisposition to non-disjunction in this family. Familial mosaic Down's syndrome was recently reported by Weiss & Wolf (1968) in two brothers with mosaic trisomy 21 and by Walker & Ising (1969) in a daughter and her father.…”

Familial translocation (3?—;G?q+) and nondisjunction of chromosome in group G in two unrelated families

“…Thus a trivalent and a univalent would be the expected configuration, as shown in Figure 4b. If segregation is alternate, the expected viable offspring would be one normal, one balanced translocation carrier and one carrier who also has trisomy G. This segregation could account for Down's syndrome in our propositi as well as in two other families reported with a trans location involving a chromosome in each of groups A and G (M iller and Dill, 1965;Kontras et a!., 1966) and in one family with a trans location involving groups C and G (W eiss and Wolf, 1968). The number of reported cases, however, is still too small to provide any statistical support for this segregation pattern.…”