Acute promyelocytic leukemia: the study of t(15;17) translocation by fluorescent in situ hybridization, reverse transcriptase-polymerase chain reaction and cytogenetic techniques.
Acute promyelocytic leukemia (AML M3) is a well-defined subtype of leukemia with specific and peculiar characteristics. Immediate identification of t(15;17) or the PML/RARA gene rearrangement is fundamental for treatment. The objective of the present study was to compare fluorescent in situ hybridization (FISH), reverse transcriptase-polymerase chain reaction (RT-PCR) and karyotyping in 18 samples (12 at diagnosis and 6 after treatment) from 13 AML M3 patients. Bone marrow samples were submitted to karyotype G-banding, FISH and RT-PCR. At diagnosis, cytogenetics was successful in 10 of 12 samples, 8 with t(15;17) and 2 without. FISH was positive in 11/12 cases (one had no cells for analysis) and positivity varied from 25 to 93% (mean: 56%). RT-PCR was done in 6/12 cases and all were positive. Four of 8 patients with t(15;17) presented positive RT-PCR as well as 2 without metaphases. The lack of RT-PCR results in the other samples was due to poor quality RNA. When the three tests were compared at diagnosis, karyotyping presented the translocation in 80% of the tested samples while FISH and RT-PCR showed the PML/RARA rearrangement in 100% of them. Of 6 samples evaluated after treatment, 3 showed a normal karyotype, 1 persistence of an abnormal clone and 2 no metaphases. FISH was negative in 4 samples studied and 2 had no material for analysis. RT-PCR was positive in 4 (2 of which showed negative FISH, indicating residual disease) and negative in 2. When the three tests were compared after treatment, they showed concordance in 2 of 6 samples or, when there were not enough cells for all tests, concordance between karyotype and RT-PCR in one. At remission, RT-PCR was the most sensitive test in detecting residual disease, as expected (positive in 4/6 samples). An incidence of about 40% of 5' breaks and 60% of 3' breaks, i.e., bcr3 and bcr1/bcr2, respectively, was observed.
Chauffaille
M L
ML
Disciplina de Hematologia e Hemoterapia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Botucatu, 740, 04023-900 São Paulo, SP, Brazil. chauffaill@hemato.epm.br
Figueiredo
M S
MS
Beltrani
R
R
Antunes
S V
SV
Yamamoto
M
M
Kerbauy
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics*; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics*; D004587:Electrophoresis, Agar Gel; D005260:Female; D015321:Gene Rearrangement; D005821:Genetic Techniques; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D007621:Karyotyping / Q000379:methods; D015473:Leukemia, Promyelocytic, Acute / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual / Q000175:diagnosis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014178:Translocation, Genetic