Two dual-color split signal fluorescence in situ hybridization assays to detect t(5;14) involving HOX11L2 or CSX in T-cell acute lymphoblastic leukemia.
OBJECTIVE
The t(5;14)(q35;q32) is a novel cryptic translocation in pediatric T-cell acute lymphoblastic leukemia (T-ALL), involving HOX11L2 or CSX on 5q35. The 14q32 breakpoints are heterogeneous. Because the t(5;14)(q35;q32) is hard to detect using conventional karyotyping, it is easily missed in routine diagnostics. Here we describe the development and application of split signal fluorescence in situ hybridization (FISH) assays for both HOX11L2 and CSX, for detection of t(5;14) possibly present in T-ALL patients.


METHODS
We developed and validated two split signal FISH assays for metaphase and interphase detection of t(5;14) in T-ALL patients. We also investigated the involvement of IGH on 14q32. In addition, HOX11L2 and SIL-TAL1 expression was studied using reverse transcription polymerase chain reaction (RT-PCR).


RESULTS
The FISH assays were validated on cell lines and T-ALL patients. We did not identify cases with a t(5;14)(q35;q32) involving CSX, but we did identify 5 cases of t(5;14) involving HOX11L2 out of 32 T-ALL cases studied; in each case the 14q32 breakpoint was found to be centromeric to the IGH region. All 5 positive cases showed HOX11L2 expression, as did 1 case without t(5;14)(q35;q32). Cases with t(5;14)(q35;q32) involving HOX11L2 did not show TAL1 abnormalities, whereas 5 HOX11L2 negative cases did.


CONCLUSIONS
Using the newly developed and validated FISH probe sets, we identified 5 new cases of t(5;14) involving HOX11L2 both on metaphases and interphases. The incidence of the t(5;14)(q35;q32) involving CSX is probably low. RT-PCR results suggest that TAL1 and HOX11L2 expression, or TAL1 aberrations and the t(5;14)(q35;q32) involving HOX11L2 are mutually exclusive.
van Zutven
Laura J C M
LJ
Department of Genetics, Erasmus MC, Rotterdam, The Netherlands.
Velthuizen
Sandra C J M
SC
Wolvers-Tettero
Ingrid L M
IL
van Dongen
Jacques J M
JJ
Poulsen
Tim S
TS
MacLeod
Roderick A F
RA
Beverloo
H Berna
HB
Langerak
Anton W
AW
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002883:Chromosomes, Human, Pair 14; D002895:Chromosomes, Human, Pair 5; D005260:Female; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D015994:Incidence; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D015513:Oncogene Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014178:Translocation, Genetic
D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; D007143:Immunoglobulin Heavy Chains; C095552:NKX2-5 protein, human; D015513:Oncogene Proteins; C489494:TLX3 protein, human; D014157:Transcription Factors