Localization of the chromosome 22 breakpoints in two cases of acute megakaryoblastic leukemia with t(1;22)(p13;q13)

Acute megakaryoblastic leukemia with t(1;22)(p13;q13) is a rare malignancy occurring in infants and young children. The genes involved in t(1;22)(p13; ql3) are unknown. In this study, dual-color fluorescence in situ hybridizat ion (FISH) experiments with 15 probes were performed on the metaphase cells obtained from one patient to systematically narrow the region of the break point on chromosome 22 and localize it to RP5-1042K10. A 22.3-kb FISH probe derived from RP5-1042KIO was used to further refine the locus of the break point in this case. Southern blot analysis covering of genomic DNA from a s econd patient detected DNA rearrangement at a site close to the breakpoint observed with the 22.3-kb probe in the first case. A partially characterize d gene, KIAA 1438, is in the vicinity of the breakpoints determined by FISH and Southern blot experiments. suggesting that this gene plays a role in t his malignancy. (C) 2001 Elsevier Science Inc. All rights reserved.