Identification of PML/RARalpha fusion gene transcripts that showed no t(15;17) with conventional karyotyping and fluorescent in situ hybridization.
Acute promyelocytic leukemia (APL) is characterized by a reciprocal translocation, t(15;17)(q22;q11-21), resulting in the fusion of the promyelocytic leukemia (PML) and retinoic acid receptor alpha (RARalpha) genes. Using conventional cytogenetic methods, these translocations are normally detected in about 70-90% of patients; most negative results are due to technical problems or cryptic variants. These masked PML/RARalpha fusions can be identified by molecular analyses, such as reverse transcriptase-polymerase chain reaction (RT-PCR) or fluorescence in situ hybridization (FISH). Approximately 5 to 10% of all APL cases reported do not show PML/RARalpha fusion transcripts, even with dual-colored FISH. We report three of 40 diagnosed APL cases that showed morphological, cytochemical, and immunophenotypic features of hypergranular APL, but did not show a PML/RARalpha fusion signal or any of its variants, on FISH. All cases were identified by RT-PCR, which was further confirmed by cDNA sequencing. Conventional karyotyping showed other clonal aberrations in these cases, but failed to show t(15;17) or any other variants or complex translocations.
Choughule
A
A
Molecular Biology Laboratory, Department of Medical Oncology, Tata Memorial Hospital, Mumbai, Maharashtra, India. anu.c1112@gmail.com
Polampalli
S
S
Amre
P
P
Shinde
S
S
Banavali
S
S
Prabhash
K
K
Nair
R
R
Subramanian
P G
PG
Gujral
S
S
Parikh
P M
PM
D000328:Adult; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics*; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D014178:Translocation, Genetic / Q000235:genetics*
D015514:Oncogene Proteins, Fusion; D012333:RNA, Messenger; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein