ABSTRACT
BACKGROUND: KRAS and NRAS gene mutations are frequently observed in childhood leukemia. The objective of this study was to determine the frequency of RAS mutations and the association between RAS mutations and other genetic aberrations in Arab Asian children with acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML). METHODS: Diagnostic samples of 485 patients (<18 years) with acute leukemia from Iraq and Jordan were obtained, using Flinders Technology Associates filter papers. Polymerase chain reaction and direct sequencing were performed in Japan. RESULTS: RAS mutations were detected in 86/318 (27%) of ALL cases and 35/167 (21%) of AML cases. The frequency of NRAS mutation was similar to that of KRAS mutation in ALL. Two RAS mutations were detected in nine patients. Among 264 Iraqi patients with ALL, RAS mutation was significantly associated with lower initial white blood cell count. Of 57 patients with chimeric transcripts, only two patients with either TEL-AML1 or E2A-PBX1 had KRAS mutation. The frequency of NRAS mutation was four times higher than that of KRAS mutation in AML. FAB-M4 and M5 subsets were associated with RAS mutation. Among 134 Iraqi patients with AML, 18 patients had RAS mutations and other genetic aberrations. In particular, 9 of 25 (36%) with MLL-rearrangement had RAS mutations. CONCLUSION: The prevalence of oncogenic RAS mutations was higher among Arab Asian children than in other countries. RAS mutations in AML were found to coexist with other genetic aberrations, particularly MLL rearrangement.
Subject(s)
GTP Phosphohydrolases/genetics , Leukemia, Myeloid, Acute/genetics , Membrane Proteins/genetics , Mutation Rate , Mutation , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Proto-Oncogene Proteins/genetics , ras Proteins/genetics , Adolescent , Arabs , Asian People , Child , Child, Preschool , Female , Histone-Lysine N-Methyltransferase , Humans , Infant , Iraq , Jordan , Leukemia, Myeloid, Acute/ethnology , Male , Myeloid-Lymphoid Leukemia Protein , Precursor Cell Lymphoblastic Leukemia-Lymphoma/ethnology , Proto-Oncogene Proteins p21(ras)ABSTRACT
BACKGROUND: RUNX1 mutation plays an important role in adult leukemic transformation. However, its contribution to the development of childhood leukemia remains unclear. In the present study, we analyzed point mutations of RUNX1 gene in children and adolescents with acute myeloid leukemia (AML) from Iraq and Jordan. PROCEDURE: Bone marrow and/or peripheral blood samples were collected from 178 patients of Arab Asian ethnicity (aged ≤17 years) newly diagnosed with AML: 145 samples from Iraq and 33 samples from Jordan. Direct DNA sequencing was performed on six genes including RUNX1 gene (exons 3-8). RESULTS: RUNX1 point mutations were identified in 10 (5.6%) of 178 patients. One patient possessed biallelic mutations of RUNX1 gene. C-terminal area was the predominant site of RUNX1 mutations (eight in C-terminal and two in N-terminal). Patients with RUNX1 mutations were significantly older than those with wild-type of the gene. Additionally, AML M0 subtype was more frequently found in patients with RUNX1 mutations. Both RUNX1 mutations and RAS mutations were identified in 4 of 10 children. Three patients with RUNX1 mutation had FLT3-ITD. On the other hand, 36 (21.4%) and 25 (14.9%) of 168 patients with wild-type of the gene had a RAS mutation and FLT3-ITD, respectively. Eight of 10 patients with RUNX1 mutations died of hematological relapse. CONCLUSION: The incidence of RUNX1 mutations in Arab Asian children and adolescents with AML was 5.6%. Further studies are required to clarify whether RAS mutations contribute to the development of pediatric AML associated with RUNX1 mutations.
Subject(s)
Core Binding Factor Alpha 2 Subunit/genetics , Genes, ras , Leukemia, Myeloid, Acute/genetics , Mutation , Adolescent , Arabs , Asian People/genetics , Child , Child, Preschool , Female , Humans , Infant , Leukemia, Myeloid, Acute/ethnology , Male , Point MutationABSTRACT
The lack of molecular diagnosis in the field of cancer in Iraq has motivated us to perform a genetic analysis of pediatric acute myelogenous leukemia (AML), including class I and II aberrations. Peripheral blood or bone marrow cells were collected from 134 AML children aged ≤15 years. Flinders Technology Associates (FTA) filter paper cards were used to transfer dried blood samples from five Iraqi hospitals to Japan. DNA sequencing was performed to identify class I mutations. Nested RT-PCR was used to detect class II aberrations, except that MLL rearrangement was detected according to long distance inverse-PCR. NPM1 and FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutations were analyzed by GeneScan using DNA template. Among 134 Iraqi pediatric AML samples, the most prevalent FAB subtype was M2 (33.6 %) followed by M3 (17.9 %). Class I mutations: 20 (14.9 %), 8 (6.0 %), and 8 (6.0 %) patients had FLT3-ITD, FLT3-TKD, and KIT mutations, respectively. Class II mutations: 24 (17.9 %), 19 (14.2 %), and 9 (6.7 %) children had PML-RARA, RUNX1-RUNX1T1, and CBFB-MYH11 transcripts, respectively. MLL rearrangements were detected in 25 (18.7 %) patients. NPM1 mutation was detected in seven (5.2 %) cases. Collectively, approximately 30 % of AML children were proved to carry favorable prognostic genetic abnormalities, whereas approximately 10 % had high FLT3-ITD allelic burden and needed a special treatment plan including allogeneic hematopoietic stem cell transplantation. Acute promyelocytic leukemia (APL) was frequent among Iraqi pediatric AML. It is likely that molecular diagnosis using FTA cards in underdeveloped countries could guide doctors towards an appropriate treatment strategy.
Subject(s)
Chromosome Aberrations , Leukemia, Myeloid, Acute/genetics , Mutation , Sequence Analysis, DNA , Specimen Handling/methods , Adolescent , Alleles , Blood Specimen Collection/instrumentation , Blood Specimen Collection/methods , Bone Marrow/pathology , Child , Child, Preschool , DNA, Neoplasm/genetics , Female , Humans , Infant , Iraq , Leukemia, Myeloid, Acute/blood , Leukemia, Myeloid, Acute/pathology , Leukemia, Myeloid, Acute/therapy , Leukemia, Myelomonocytic, Acute/blood , Leukemia, Myelomonocytic, Acute/genetics , Leukemia, Myelomonocytic, Acute/pathology , Leukemia, Myelomonocytic, Acute/therapy , Male , Nucleophosmin , Oncogene Proteins, Fusion/genetics , Oncogenes , Paper , Prognosis , Reverse Transcriptase Polymerase Chain Reaction , Specimen Handling/instrumentation , Translocation, Genetic , Treatment OutcomeABSTRACT
BACKGROUND: Genetic examination of childhood leukemia has not been available in Iraq. We here report the frequency of TEL-AML1, E2A-PBX1, MLL-AF4, and BCR-ABL chimeric transcripts in 264 Iraqi children newly diagnosed with acute lymphoblastic leukemia (ALL), using FTA cards impregnated with bone marrow aspirate or whole blood. PATIENTS AND METHODS: The diagnosis of ALL was made according to standard French-American-British morphologic criteria. Based on the results of storage temperature and duration, most of the FTA samples were preserved at 4°C for up to 6 weeks in five Iraqi hospitals and then transferred to Japan for molecular analysis. Nested reverse transcription-polymerase chain reaction was adopted for the analysis. RESULTS: TEL-AML1 chimeric transcript product was found in 32 (12.1%) of 264 ALL patients. Eleven (4.2%) patients, 4 (1.5%) patients, and 11 (4.2%) patients had E2A-PBX1 mRNA, MLL-AF4 mRNA, and BCR-ABL mRNA, respectively. One patient had both TEL-AML1 and E2A-PBX1 fusion genes. The incidence of TEL-AML1 in Iraqi ALL children appears to be similar to or slightly higher than those of Jordan (12%) and Kuwait (7%). The prevalence and clinical findings of ALL patients with either E2A-PBX1 or BCR-ABL were comparable to the data reported elsewhere. CONCLUSION: International collaboration via FTA cards may be helpful to improve diagnosis and management of patients with hematological malignancies in low-income and underdeveloped countries.
