Chronic myelogenous leukemia with translocations (3q-;9q+) and (17q-;22q+). Possible crucial cytogenetic events in the genesis of CML.

Two reciprocal translocations involving chromosomes 3, 9, 17, and 22 were found in a patient with seemingly Ph1-negative chronic myelogenous leukemia (CML). The two translocations were t(3;9)(q21;q34) and t(17;22)(q21;q11); the breakage in chromosomes 9 and 22 apparently occurred at the same point as in the usual Ph1 translocation, t(9;22)(q34;11). From the present evidence and a review of the literature it appears that the breakage on both chromosomes 9 and 22 at the special regions and the separation of the fragments are present in practically all standard and variant Ph translocations, even those in which the terminal region of the long arm of chromosome 9 and (9q) does not seem to be involved in the rearrangement; however, a translocation between chromosomes 9 and 22 is not an obligatory result of the rearrangement, as seen in the present case. Thus, we postulate that the breakage on both chromosomes 9 and 22 at the special regions and separation of the fragments are the crucial cytogenetic events in the genesis of CML and stress the importance of paying careful attention to the terminal region of 9q, particularly when chromosome 9 does not seem to be involved in the rearrangement.