Nonrandom rearrangements of 6p in malignant hematological disorders.

It is very uncommon to observe nontranslocation abnormalities (NTAs) involving the short arm of chromosome 6 (6p) in malignant hematological disorders (MHDs). By using conventional cytogenetics and fluorescence in situ hybridization (FISH) with chromosome-microdissection probes specific for 6p21 and 6p25, we observed five patients with myeloid malignancies and two patients with lymphoid malignancies to have 6p NTAs. On the basis of our data and those in the literature, it is possible to divide 6p NTAs into the following three groups in MHD: The first group presents with 6p NTAs as a sole or primary change in myeloid malignancies. There are only two cases reported in this group, including one case with del(6)(p23) and the present case with ins(6)(q23p23p25) identified by FISH only. The second group presents with 6p deletions as a sole or primary change in lymphoid malignancies. Three cases have been reported in this group, including one case with del(6)(p21p23), one with del(6)(p21), and the present case 2 with del(6)(p21). The third group has 6p deletions in addition to other known primary changes, present in both myeloid and lymphoid disorders, with 36 cases reported, including five cases from our series. Deletions involving 6p21, 6p22, or 6p23 have been observed in both myeloid and lymphoid disorders. The present data provide cogent information for further molecular characterization of 6p anomalies in MHD.