On the 5q- deletion: clinical and cytogenetic observations in ten patients and review of the literature. 
Clinical and cytogenetic findings in 10 patients with deletions of the long arm of chromosomes 5 (5q-) are reported.  Five cases had refractory anemia, the preleukemic syndrome, or refractory anemia with an excess of blasts; in all but one, the 5q- was the single initial abnormality.  Three patients had overt leukemia; in all, the 5q- was accompanied by additional anomalies.  Two patients had a myeloproliferative disorder.  In one of these, a case of polycythemia vera, the 5q- appeared secondarily to other karyotypic abnormalities and concomitantly with transformation into a "spent phase."  The deletions were interstitial in most cases, and even if the size of the deletion varied, the region q15-q31 was lost in all cases except 2.  Bone marrow from all cases except one showed a marked increase in the number of megakaryocytes.  A survey of the literature yielded a total of 69 evaluable patients with 5q- deletions, including the present series.  The 5q- has now been observed in a wide spectrum of hematologic disorders.  However, most cases had either preleukemia (39%) or leukemia (46%).  When detected during preleukemia, the 5q- usually appeared alone (74%), while during overt leukemia it regularly was accompanied by other abnormalities (88%).