In summary, of 64 patients with total or partial monosomy 7, 21 cases showed a deletion of 7q, and a translocation resulting in loss of the whole or major portion of 7q was detected in six other cases; a consistent translocation involving chromosomes #7 and #17 was observed in four of the latter cases, resulting in an effective loss of 7q. In 23 of these 27 patients reviewed with loss of 7q, the common segment deleted involved 7q32 to 7q34 (Table). The most common abnormalities associated with -7 or 7q- were -5 or 5q- (26 cases) and monosomy 17 (16 cases); except for two patients, all of the latter also had -5 or 5q-. Fifteen of the 64 patients with -7 or 7q- had a secondary leukemia (23.4%). Other abnormalities, such as complete and partial trisomy 7 and various balanced translocations involving #7, were far less common. Only one of 16 cases had an associated 5q- chromosome, one was -17, and only one case had secondary leukemia.