Trisomy and tetrasomy for long arm of chromosome 1 in near‐diploid human endometrial adenocarcinomas

Karyotypic analysis by R‐banding after short‐term culture, carried out on 7 cases of human endometrial adenocarcinoma, showed in 4 of these a trisomy or a tetrasomy for the long arm of chromosome I. In the 4 cases, these imbalances were due to rearrangements involving centromeric or para‐centromeric breakpoints: 46, XX,−16, + der(1q16p) t(1;16)(1p16q;1q16p); 46, XX,−21, + der(1q21q) t(1;21)(1p21p;1q21q);46, XX,−21, + der(21) t(1;21)(q11;p13); 48, XX, +2, + i(1q). Two other cases showed only a numerical aberration: 47, XX, + 10 and 47, XX, + 12. In the last case, only cells with apparently normal karyotype were seen. In the 4 cases with an anomaly of chromosome I, two normal I chromosomes coexisted with abnormal elements. This shows that the rearrangement very likely occurred in G 2 phase of the cell cycle.