Detection of fusion genes in formalin-fixed paraffin-embedded tissue sections of rhabdomyosarcoma by RT-PCR and fluorescence in situ hybridization in Mexican patients.
OBJECTIVE
Rhabdomyosarcoma (RMS) is a pediatric tumor whose classification is based on histological criteria according to two main subgroups, embryonal RMS (ERMS) and alveolar RMS (ARMS). The majority but not all ARMS carry the specific PAX3(7)/FKHR translocation. The type of translocation in patients with ARMS defines the prognosis.


METHODS
We retrospectively analyzed 30 cases of ARMS in Mexican patients and evaluated the fusion status of the genes using RT-PCR and fluorescence in situ hybridization (FISH) in formalin-fixed paraffin-embedded tissues (FFPET).


RESULTS
From 25 samples (83%) with optimal RNA quality, RT-PCR revealed 15 cases (50%) with the t(2;13)/PAX3-FKHR. Only one case (3%) was positive to t(1;13)/PAX7-FKHR and nine cases (30%) were fusion-negative. Correspondingly, using FISH, the t(2;13)/PAX3-FKHR was found positive in 19 cases (63.5%), one case (3%) revealed the t(1;13)/PAX7/FKHR and ten cases (33.5%) were fusion-negative by this method. Five cases were not evaluable by RT-PCR but recovered by FISH. Only four of the total revealed t(2;13); the other was fusion-negative.


CONCLUSIONS
FISH technique is more sensitive when FFPET is used to describe the chromosomal translocation of ARMS. These Latino patients showed an association of the t(2;13) in older patients (mean: 9 years) and negative translocation in younger patients (mean: 4 years) (p <0.05). Both t(2;13) and negative-fusion were present in patients with clinical stages III and IV (p <0.05). There was a nonsignificant trend of t(2;13) to lower overall survival than negative-fusion status.
Eguía-Aguilar
Pilar
P
Departamento de Patología, Hospital Infantil de México Federico Gómez, México, D.F., México.
Ponce-Castañeda
Verónica
V
Nájera-García
Nayelli
N
Nieto-Martínez
Karem
K
Kofman-Alfaro
Susana
S
Sadowinski-Pine
Stanislaw
S
Valencia-Mayoral
Pedro
P
Arenas-Huertero
Francisco
F
Perezpeña-Diazconti
Mario
M
D002648:Child; D005557:Formaldehyde; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D053208:Kaplan-Meier Estimate; D008800:Mexico; D016612:Paraffin Embedding; D011993:Recombinant Fusion Proteins / Q000235:genetics*; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012208:Rhabdomyosarcoma / Q000145:classification / Q000235:genetics* / Q000401:mortality / Q000473:pathology
D011993:Recombinant Fusion Proteins; D005557:Formaldehyde