Table 2.
Cytogenetic and molecular classification according to the World Health Organization (WHO) in 86 children and adolescents with acute myeloid leukemia (AML).
| Characteristics | Number | % |
|---|---|---|
| Cytogenetic alterations | ||
| Normal karyotype | 17 | 21.3 |
| t(15;17)(q22;q21) | 21 | 26.2 |
| t(8;21)(q22;q22) | 7 | 8.8 |
| inv(16)(p13.1q22) or t(16;16)(p13.1;q22) | 2 | 2.5 |
| t(9;11)(p22;q23) | 2 | 2.5 |
| AML (megakaryoblastic) with t(1;22)(p13;q13) | 2 | 2.5 |
| AML with myelodysplasia-related changes: -5/del(5q), -7/del(7q), del(11q), del(12p)/t(12p), and del(13q) | 13 | 16.2 |
| Other chromosomic abnormalities | 16 | 20.0 |
| Totala | 80 | 100 |
| Fusion genes and specific mutations | ||
| PML-RARA | 25 | 31.6 |
| PML-RARA and FLT3-ITD | 2 | 2.5 |
| CBFB-MYH11 | 3 | 3.8 |
| AML1-ETO (RUNX1-RUNX1T) | 5 | 6.3 |
| BCR-ABL | 0 | 0 |
| FLT3-ITD (as the single abnormality) | 3 | 3.8 |
| Negative tests for the above-mentioned abnormalities | 41 | 52.0 |
| Totalb | 79 | 100 |
| WHO classification | ||
| AML with recurrent genetic abnormalities | 45 | 52.3 |
| t(8;21)(q22;q22)/RUNX1-RUNX1T | 9 | |
| inv(16)(p13.1q22)/CBFB-MYH1 | 3 | 18.6 |
| t(15;17)(q22;q21)/PML-RARA | 29 | |
| t(9;11)(p22;q23) | 2 | 22 |
| AML (megakaryoblastic) with t(1;22)(p13;q13) | 2 | |
| AML with myelodysplasia-related changes | 16 | 7 |
| -7/del(7q) | 4 | |
| -5/del(5q) | 2 | 100 |
| del(11q) | 5 | |
| -13/del(13q) | 1 | |
| del(12p) or t(12p) | 1 | |
| AML secondary to myelodysplastic syndrome | 1 | |
| Complex karyotype | 2 | |
| AML not otherwise specified | 19 | |
| Normal karyotype | 11 | |
| Other abnormalities | 8 | |
| Myeloid leukemia associated with Down syndrome | 6 | |
| Normal karyotype (except for the constitutional abnormality) | 1 | |
| Numerical chromosomal abnormalityc | 2 | |
| Structural chromosomal abnormalityd | 1 | |
| No metaphases for cytogenetic study | 1 | |
| Not registered in medical file | 1 | |
| Totale | 86 | |
Additionally, in 10 patients metaphases were not present for cytogenetic analysis and in 8 patients cytogenetic restults were not registered in medical files.
Additionally, in 16 patients molecular studies were not requested at diagnosis and in three patients DNA/cDNA amplification was not successful.
In two patients, in addition to constitutional chromosome +21, extra chromosomes were detected: one patient had +8 and another +19 and +22.
Patient with der(22)t(1;22)(q25;q13). in addition to constitutional chromosome +21.
Additionally, in 12 patients no cytogenetic or molecular data were retrieved from their medical files and, accordingly, they were not included in the WHO classification.