Precise localization by microdissection/reverse ISH and FISH of the t(15;17)(q24;q21.1) chromosomal breakpoints associated with acute promyelocytic leukemia.

The acute promyelocytic leukemia (APL M3)-associated translocation (15;17) has been described as having breakpoints variably located between 15q22 and 15q26, and 17q11 and 17q25. Most of the recent studies using DNA probes (fluorescence in situ hybridization [FISH]) for analysis have indicated the chromosome 15 breakpoint to be in 15q22. We have utilized a combination of G-banding, FISH, and chromosome microdissection/reverse ISH to precisely map the breakpoint to t(15;17)(q24;q21.1).