MTHFR 677C-->T and 1298A-->C polymorphisms in children with Down syndrome and acute myeloid leukemia in Brazil.

Down syndrome (DS) is an important risk factor associated with acute leukemia (AL). The presence of polymorphisms that reduce 5,10-methylenetetrahydrofolate reductase (MTHFR) activity has been linked to the multifactorial leukemogenic process. The authors have conducted a study to test whether 677C-->T and/or 1298A-->C polymorphisms of MTHFR would play an additional role in susceptibility of acute myeloid leukemia (AML) in DS children. They also verified whether any polymorphism in the MTHFR gene was associated with the risk of DS. Genetic polymorphisms determination was carried out in 248 samples from healthy individuals as controls and a total of 115 DS children (65 without leukemia and 50 with AML). The present study failed to reveal any association between these polymorphisms and risk of AML in DS children. The data also indicate that MTHFR polymorphisms are not associated with risk of being a DS child.

Lowered Cisplatin Dose and No Bleomycin in the Treatment of Pediatric Germ Cell Tumors: Results of the GCT-99 Protocol From the Brazilian Germ Cell Pediatric Oncology Cooperative Group.

PURPOSE: We describe the results of a risk-adapted, response-based therapeutic approach from the Brazilian GCT-99 study on germ cell tumors. PATIENTS AND METHODS: From May 1999 to October 2009, 579 participants were enrolled in the Brazilian GCT-99 study. Treatment, defined as specific chemotherapy regimen and number of cycles, was allocated by means of risk-group assignment at diagnosis with consideration for stage and primary tumor site. Patients at low risk received no chemotherapy. Patients at intermediate risk (IR) with a good response (GR) received four cycles of platinum and etoposide (PE), for total doses of platinum 420 mg/m(2) and etoposide 2,040 mg/m(2). Patients at IR with a partial response (PR) received three cycles of PE plus three cycles of ifosfamide, vinblastine, and bleomycin. Patients at high risk (HR) with a GR received four cycles of PE and ifosfamide (PEI) at total doses of platinum 420 mg/m(2), etoposide 1,200 mg/m(2), and ifosfamide 30 g/m(2). Patients at HR with a PR received six cycles of PEI. RESULTS: The risk-group distribution was 213 LR, 138 IR, and 129 HR for 480 evaluable patients. Overall survival (OS) and event-free survival (EFS) rates at 10 years were, respectively, 90% and 88.6% in the IR-GR group (n = 126) and 74.1% and 74.1% in the IR-PR group (n = 12). Ten-year rates for the HR-GR group (n = 86) were an OS of 66.8% and an EFS of 62.5%. The HR-PR group (n = 43) had an OS of 74.8% and an EFS of 73.4%. In univariable and multivariable analysis, increased serum lactate dehydrogenase level and histology for a metastatic immature teratoma were prognostic of a worsened outcome. CONCLUSION: Reduction of therapy to two drugs did not compromise survival outcomes for patients in the IR-GR group, and escalation of therapy with PEI did not significantly improve OS and EFS in patients at HR.

Clinical and molecular epidemiology of neonatal leukemia in Brazil.

The clinical and molecular findings of 77 cases of neonatal leukemia (NL) and 380 of infant leukemia (IL) were selected to distinguish features between NL and IL. Somatic gene mutations associated with acute leukemia including FLT3, RAS and PTPN11 were revisited. There were 42 cases of congenital leukemia associated with Down syndrome (DS) and 39 of these cases presented features of acute myeloid leukemia (AML)-M7. Twenty-seven of the DS cases underwent spontaneous remission and were reclassified as a transient myeloproliferative disorder. GATA1 mutations were found in 70% of these cases. In non-DS, frequent abnormalities were MLL rearrangements, mainly MLL-AFF1 in acute lymphoblastic leukemia and MLL-MLLT3 in AML. The FLT3 mutation was not found, while RAS (n = 4) and PTPN11 (n = 2) mutations were identified and reported for the first time in NL. There was substantial evidence to support that somatic abnormalities occur in utero. Thus, congenital leukemia is a good model for understanding leukemogenesis.

Detection of mutations in GATA1 gene using automated denaturing high-performance liquid chromatography and direct sequencing in children with Down syndrome.

Denaturing high-performance liquid chromatography (dHPLC) was developed to screen DNA variations by separating heteroduplex and homoduplex DNA fragments by ion-pair reverse-phase liquid chromatography. In this study, we have evaluated the dHPLC screening method and direct sequencing for the detection of GATA1 mutations in peripheral blood and bone marrow aspirates samples from children with Down syndrome (DS). Cases were ascertained consecutively as part of an epidemiological study of DS and hematological disorders in Brazil. A total of 130 samples corresponding to 115 children with DS were analysed using dHPLC and direct sequencing methods to detect mutations in GATA1 exons 2, 3 and 4 gene sequences. The overall detection rate of sequencing and dHPLC screening methods was similar. Twenty mutations were detected in exon 2 and one mutation in exon 3 (c.231_232 dupGT) sequences of acute megakaryoblastic leukemia and transient leukemia samples. Four GATA1 mutations were newly described [c.155C > G; c.156_178 del23 bp; c.29_30 del GG; c.182C > A and c.151A > T,c.153_162 del 10 bp). Out of four, three had single nucleotide change. In conclusion, our results indicate that dHPLC is an efficient and valuable tool for GATA1 mutational analysis.