Y-chromosome loss as the sole karyotypic anomaly with 3'RARalpha submicroscopic deletion in a case of M3r subtype of acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is characterized by the presence of a chromosomal rearrangement involving retinoic acid receptor alpha (RARalpha) gene generating the X-RARalpha fusion. We describe here a unique RARalpha gene rearrangement in a patient with M3r subtype of APL. Conventional cytogenetic analysis revealed Y-chromosome loss as the sole karyotypic anomaly. No X-RARalpha fusion was detected by fluorescence in situ hybridization (FISH) using PML/RARalpha dual-color dual-fusion translocation probe set, or RARalpha dual-color break apart rearrangement probe or reverse-transcription polymerase chain reaction (RT-PCR). However, FISH using RARalpha dual-color break apart rearrangement probe showed a deletion of the entire 3'-end of one allele of RARalpha gene. To our knowledge, this is the first documented APL with 3'RARalpha submicroscopic deletion which is not associated with X-RARalpha fusion. The molecular consequences of this anomaly remain to be elucidated.