OBJECTIVETo explore the application of combined detection of fusion gene and BIOMED-2 standardized immunoglobulin (Ig) gene rearrangement system in diagnosis and treatment of children with acute lymphoblastic leukemia (ALL).

METHODSMultiplex-PCR amplifications and RQ-PCR of RNA/DNA were performed using ALL fusion gene detection kit and BIOMED-2 primer. The Ig gene rearrangements were analyzed by using PCR fragment analysis system.

RESULTSOut of 251 children with B-ALL, 77 cases were TEL-AML1(+) , 28 cases were E2A-PBX1(+) , 10 cases were MLL-AF4(+) , 11 cases were BCR-ABL(+) , the total positive rate was 50.2%, 82.5% showed IgH VH-JH rearrangement, 53.4% showed IgK rearrangement. The positive rate of combined detection of fusion gene and gene rearrangement was 99%. E2A-PBX1(+) and MLL-AF4(+) with IgK(+) gene rearrangement group was compared with negative control group, the difference was statistically significant (P < 0.001 or P = 0.005); 105 ALL fusion gene positive cases had been detected by fluorescence in situ hybridization (FISH) simultaneously, the accordance rate of fusion gene and FISH was more than 94%.

CONCLUSIONThe combined detection of ALL fusion gene and BIOMED-2 standardized clonality analysis system can improve the positive detected rate of B-ALL dramatically, and make the grouping of disease prognosis more accurately; this combined detection is a more faster and sensitive method than FISH.

Child ; Core Binding Factor Alpha 2 Subunit ; genetics ; DNA Primers ; Fusion Proteins, bcr-abl ; genetics ; Humans ; In Situ Hybridization, Fluorescence ; Multiplex Polymerase Chain Reaction ; Oncogene Proteins, Fusion ; genetics ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; diagnosis ; genetics ; V(D)J Recombination

BACKGROUNDThe FIP1L1-PDGFRalpha fusion gene plays an important role in the pathogenesis of chronic eosinophilic leukemia (CEL) and is a direct therapeutic target of the tyrosine kinase inhibitor imatinib mesylate.

METHODSIn 24 hypereosinophilic syndromes (HES) patients, using reverse transcriptase-polymerase chain reaction (RT-PCR), nested PCR and sequence analysis, we investigated the frequency of FIP1L1-PDGFRalpha and other abnormalities of tyrosine kinase family genes like PDGFRalpha, PDGFRbeta, C-KIT, FGFR1, ABL and FLT3 as well as gene mutation "hotspots", like MPL515 and JAK2V617F, frequently involved in myeloproliferative diseases. Fluorescence in situ hybridization was used to confirm the 4q12 deletion.

RESULTSThe FIP1L1-PDGFRalpha fusion transcript was found in 8 (33%) of 24 patients with HES, corresponding to the chromosome 4q12 deletion identified by FISH. The FIP1L1-PDGFRalpha-associated patients diagnosed with CEL, frequently had hepatosplenomegaly, eosinophil-related tissue damage, anemia, thrombocytopenia, myelofibrosis and a short overall survival time. Nevertheless, imatinib mesylate induced rapid and complete hematological responses in treated FIP1L1-PDGFRalpha cases, followed by molecular remission and reversal of myelofibrosis. FIP1L1-PDGFRalpha fusion could co-exist with other mutations of tyrosine kinase family genes, like FLT3 or PDGFRbeta. We also demonstrated that the SNPs of PDGFRbeta were associated with selective splicing of exon 19 in case 20.

CONCLUSIONSCorrelating the CEL genotype with phenotype, FIP1L1-PDGFRalpha emerges as a relatively homogeneous clinicobiological entity that co-exists with other abnormalities of tyrosine kinase family genes. It reflects the disease progression and there is a good response to imatinib. Detection of the FIP1L1-PDGFRalpha fusion gene is valid for both CEL diagnosis and therapy surveillance.

Adolescent ; Adult ; Aged ; Antineoplastic Agents ; therapeutic use ; Benzamides ; Chronic Disease ; Disease Progression ; Female ; Genotype ; Humans ; Hypereosinophilic Syndrome ; drug therapy ; genetics ; pathology ; Imatinib Mesylate ; In Situ Hybridization ; Male ; Middle Aged ; Mutation ; Oncogene Proteins v-abl ; genetics ; Oncogene Proteins, Fusion ; genetics ; Phenotype ; Piperazines ; therapeutic use ; Polymorphism, Single Nucleotide ; Proto-Oncogene Proteins c-kit ; genetics ; Pyrimidines ; therapeutic use ; Receptor, Fibroblast Growth Factor, Type 1 ; genetics ; Receptor, Platelet-Derived Growth Factor alpha ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; fms-Like Tyrosine Kinase 3 ; genetics ; mRNA Cleavage and Polyadenylation Factors ; genetics