Cytogenetic analysis in children with acute nonlymphocytic leukemia

A cryptic three-way translocation t(10;19;11)(p12.31;q13.31;q23.3) with a derivative Y-chromosome in an infant with acute myeloblastic leukemia (M5b)

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the malignant transformation of hematopoietic precursors to a pathogenic cell clone. Chromosomal band 11q23 harboring MLL (=mixed lineage leukemia) gene is known to be involved in rearrangements with variety of genes as activating partners of MLL in different AML subtypes. Overall, an unfavorable prognosis is associated with MLL abnormalities. Here we investigated an 11-month-old male presenting with hyperleukocytosis being diagnosed with AML subtype FAB-M5b. In banding cytogenetics a der(19)t(19;?)(q13.3;?) and del(Y)(q11.23) were found as sole aberrations. Molecular cytogenetics revealed that the MLL gene was disrupted and even partially lost due to a t(10;19;11)(p12.31;q13.31;q23.3), an MLL/MLLT10 fusion appeared, and the der(Y) was an asymmetric inverted duplication with breakpoints in Yp11.2 and Yq11.23. The patient got hematopoietic stem cell transplantation from his haploidentical mother. Still three months afterwards 15% of blasts were detected in bone marrow and later the patient was lost during follow-up. The present case highlights the necessity to exclude MLL rearrangements, even when there seems to be no actual hint from banding cytogenetics.

Global characteristics of childhood acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) comprises approximately 5-10% of childhood acute myeloid leukemia (AML) cases in the US. While variation in this percentage among other populations was noted previously, global patterns of childhood APL have not been thoroughly characterized. In this comprehensive review of childhood APL, we examined its geographic pattern and the potential contribution of environmental factors to observed variation. In 142 studies (spanning >60 countries) identified, variation was apparent-de novo APL represented from 2% (Switzerland) to >50% (Nicaragua) of childhood AML in different geographic regions. Because a limited number of previous studies addressed specific environmental exposures that potentially underlie childhood APL development, we gathered 28 childhood cases of therapy-related APL, which exemplified associations between prior exposures to chemotherapeutic drugs/radiation and APL diagnosis. Future population-based studies examining childhood APL patterns and the potential association with specific environmental exposures and other risk factors are needed.

HLA-DR(negative), CD34(negative) hypergranular acute myeloid leukemia with trisomy 6 and del(5)(q22q33): case report and review of the literature

We report a unique pediatric case of hypergranular acute myeloid leukemia with myelodysplasia-related changes. The patient presented with moderate leukocytosis with neutrophilia with left-shift maturation and dysplasia, anemia, and multiple sclerotic bone lesions. The bone marrow was hypercellular with a predominance of myeloblast cells and/or abnormal promyelocytes with hypergranular cytoplasm. Flow cytometric immunophenotyping showed that the leukemic cells were positive for CD13, CD33, and myeloperoxidase, and negative for HLA-DR and CD34. Morphology and immunophenotyping were highly suggestive of acute promyelocytic leukemia. The classic t(15;17) or other RARα rearrangements were not detected by cytogenetic or molecular assays, ruling out acute promyelocytic leukemia. Standard cytogenetic analysis showed that the karyotype of the predominant clone was 47,XY,+6 with evidence of clonal evolution to 47,XY,+6,del(5)(q22q33). A literature and database review showed that trisomy 6 is a rare occurrence in hematological malignancies and, to our knowledge, has never been reported in association with del(5)(q22q33) in a child presenting with hypergranular acute myeloid leukemia with myelodysplasia-related changes. We present a current review of the literature and summarize the clinical features of 57 cases of trisomy 6 as the primary chromosomal abnormality in hematological disease.

Chronic myeloid leukemia with a rare variant Philadelphia translocation: t(9;10;22)(q34;q22;q11)

We report a 59-year-old, male, chronic myeloid leukemia patient with a rare variant Philadelphia (Ph) translocation t(9;10;22)(q34;q22;q11). Fluorescence in situ hybridization with whole chromosome paints was used to confirm the cytogenetic findings. With a BCR/ABL-specific probe, the known rearrangement on the derivative chromosome 22 was found. The prognostic implications as well as the relevance of the additional breakpoint region 10q22 are discussed.

Comparative genomic hybridization and conventional cytogenetic analyses in childhood acute myeloid leukemia

Comparative genomic hybridization (CGH) analysis was performed on bone marrow specimens from 19 children with acute myeloid leukemia (AML) at diagnosis. The results of CGH were compared to those of conventional cytogenetic analysis. The most common CGH aberrations were gains of whole chromosomes 6 and 8, both of which appeared three times. Two losses were seen twice; losses of whole chromosomes 7 and X. The CGH findings were concordant with the results of conventional karyotyping. CGH did not add new information to the karyotypes. Since no high-level amplification was found among the samples and standard karyotyping was highly successful, we do not advocate routine use of CGH in the diagnostic evaluation of childhood AML.

Cytogenetic, cytomorphologic, and immunologic analysis in 55 children with acute lymphoblastic leukemia

This paper presents the results of cytogenetic analysis in 55 children with acute lymphatic leukemia (ALL). Acquired chromosome aberrations were identified in 35 (63.6%) children. Difference in frequency of clonal aberrations depending on age of patients was observed. Thus, acquired aberrations were detected in all three children up to 6 months of age, in 57.8% in the group from 1-10 years, and in six (85.7%) of seven children older than 10 years of age at diagnosis. The analysis revealed chromosome aberrations specific for ALL. Hyperdiploidy >50 was identified in 20% of children, and the association with CALLA+ early pre-B and L2-ALL was observed. del(6) and t(1;19) were identified in 7.3% and 5.5% of children, respectively. No association with a specific morphology or specific immunophenotype for both structural aberrations has been established. The association of structural aberrations involving regions 14q11-12 and T-cell ALL, however, has been observed, as an aberration was identified in two (3.6%) children, i.e., in 25% of our T-cell leukemias. Interstitial deletion of the long arm of chromosome 13, a rare chromosomal aberration in ALL, was identified in addition to del(9)(q31) in a 17-month-old girl with constitutional trisomy of chromosome 21 and B-cell ALL-L2. Interesting is the finding of hyperdiploidy with 52 chromosomes and structural aberrations of chromosome 1 in a 1-month-old girl with morphologically unclassified CALLA+ pre-T acute leukemia. To our knowledge this is the first case of hyperdiploidy >50 in a neonatal leukemia.

A chromosome study on 97 cases of acute nonlymphocytic leukemia M2

Chromosomal studies were performed in the same laboratory on 97 untreated cases of de novo acute nonlymphocytic leukemia M2. The overall incidence of chromosomal abnormality was 70.1% (68 out of 97 cases), which was higher in children (84.2%) than in adults (61%). The male to female chromosomal abnormality ratio was nearly the same (male 71% and female 68.4%, P > 0.05). Hypodiploidy was the most common numerical abnormality (39%) and t (8; 21) was the most common structural abnormality (48.1%). In the patients with t(8; 21), 64.5% (20 out of 31 cases) male lost chromosome Y (-Y) and 33% (5 out of 15 cases) female lost one chromosome X (-X).