Preferential Involvement of Chromosomes No . 8 and No .

Chromosome analyses were performed by isted in the chromosome changes; the nona direct method on bone marrow cells of random occurrence of some chromosome 147 patients with acute leukemia and preabnormalities was revealed, involving leukemia; in 53 chromosomally abnormal most frequently chromosomes No. 8 and cell lines were found. Chromosome abNo. 2 1 . Abnormalities of chromosome No. normalities due to structural alterations 22 were not encountered, contrasting were observed in 48% of the aneuploid sharply with the frequent involvement of patients. Using the ASG banding techthis chromosome in chronic myelogenous nique, the exact identification of the ableukemia. The significance of the prefnormal chromosomes was successfully erential involvement of No. 8 and No. 21 made in 22 aneuploid patients. Even chromosomes is discussed in relation to though variability between patients cxleukemogenesis. T HE EXACT IDENTIFICATION of individual human chromosomes could not be established with certainty until recently. However, it is now possible to identify rigorously with newly developed chromosome banding techniques each chromosome pair, parts of chromosomes, and those involved in chromosomal rearrangements. A rapid expansion ofour knowledge in chromosome cytology has been brought about by these new techniques. In chronic myelocytic leukemia (CML) it has been demonstrated that the Philadelphia chromosome (Ph’) is a deleted No. 22 chromosome and that the deleted segment most often is translocated onto chromosome No. 9#{149}I These methods also make possible a detailed analysis of the chromosomes in acute leukemia and related states, particularly regarding the random or nonrandom involvement of certain chromosomes in the karyotypic abnormalities of these disease states. We wish to describe chromosome studies in patients with acute leukemia or preleukemic disorders, based on the identification of abnormal chromosomes with banding techniques, and to demonstrate a possible nonrandomness of the chromosome abnormalities in the leukemic and preleukemic cells.