Characteristics of fusion gene and immunophenotype in MLL gene rearrangement positive childhood acute lymphoblastic leukemia / 中国实验血液学杂志

The study was aimed to investigate the fusion gene transcript and immunophenotypic characteristics of the mixed linage leukemia (MLL)-rearranged positive childhood acute lymphoblastic leukemia (ALL). The incidence of MLL rearrangement in 601 cases of ALL patients was detected by the multiple-nested polymerase chain reaction (PCR); the subtypes and features of the fusion gene transcript were analyzed by PCR products sequencing; the immunophenotypic characteristics at diagnosis were compared between the 22 MLL rearrangement positive of ALL patient, 30 negative control which selected randomly from the patients whose fusion gene could not be detected in the same term and 43 pro-B-ALL patients. The results showed that the incidence of MLL positive ALL was 3.66%, constituted 29.9% of the pro-B-ALL. The MLL rearrangement positive 20 B-ALL patients were all CD10 negative; the number of patients who carried CD13, CD33 and CD34 was lower than that of pro-B-ALL who had no fusion gene, whereas the expression of CD20, CD22, CD2, CD5, CD7 showed no difference. 4 kind partner genes of MLL-AF4, AF9, AF10 and ENL were detected. The fusion loci of MLL gene were mainly located at the exon 6, 7, 8 and many kind of fusion loci of MLL may exist in one patient; whereas its partner gene fusion loci were relatively single. A transcript contains a random insert sequence existed in a transcript of one MLL-AF10+ patient. It is concluded that though incidence of MLL rearrangement is low, but it has a variety of fusion transcripts, the ALL patients has unique biological characteristics at immunophenotype and fusion transcript.

Immunophenotypic characteristics of children with acute lymphoblastic leukemia carrying TEL-AML1 fusion gene / 中国实验血液学杂志

To investigate the immunological and other clinical characteristics in TEL/AML1+ childhood B-acute lymphoblastic leukemia (B-ALL), immunophenotyping was performed with three-color flow cytometry, and the expression of TEL-AML1 fusion gene was detected with nested RT-PCR. Diagnosis was made according to FAB and MIC criteria. The results showed that (1) among 119 children with B-ALL, 22 (18.5%) were TEL-AML1 positive and classified as L2 morphological subtype. In TEL-AML1+ group, positive rate and score of PAS, which were 65% and 121 respectively, were all higher than that of TEL-AML1- group (P < 0.05); (2) compared with TEL-AML1- group, no significant difference was found in age, gender, white cell count and blasts count in peripheral blood of TEL-AML1+; (3) in TEL-AML1+ group, 21 out of 22 (95.5%) were common ALL, as compared with TEL-AML1- group, the positive rate of CD13 was higher (59.1%, 13/22) and the positive rate of CD20 was lower (22.7%, 5/22) than that in TEL-AML1- group, respectively (P < 0.05), and the mean fluorescence index of CD10 and HLA-DR significantly increased to 92.80 and 53.61, respectively (P < 0.05). It is concluded that TEL-AML1 rearrangement is a frequent molecular abnormality in childhood ALL. Leukemic blasts with this anomaly have special immunophenotypic characteristics. These characteristics may be useful in detection of minimal residual leukemia.