Cytogenetic studies of Brazilian pediatric myelodysplastic syndrome cases: challenges and difficulties in a large and emerging country

Myelodysplastic syndromes (MDS) and juvenile myelomonocytic leukemia (JMML) are rare hematopoietic stem cell diseases affecting children. Cytogenetics plays an important role in the diagnosis of these diseases. We report here the experience of the Cytogenetic Subcommittee of the Brazilian Cooperative Group on Pediatric Myelodysplastic Syndromes (BCG-MDS-PED). We analyzed 168 cytogenetic studies performed in 23 different cytogenetic centers; 84 of these studies were performed in patients with confirmed MDS (primary MDS, secondary MDS, JMML, and acute myeloid leukemia/MDS+Down syndrome). Clonal abnormalities were found in 36.9% of the MDS cases and cytogenetic studies were important for the detection of constitutional diseases and for differential diagnosis with other myeloid neoplasms. These data show the importance of the Cooperative Group for continuing education in order to avoid a late or wrong diagnosis.

TRAP-silver staining, a highly sensitive assay for measuring telomerase activity in tumor tissue and cell lines

Measurement of telomerase activity in clinically obtained tumor samples may provide important information for use as both a diagnostic marker and a prognostic indicator for patient outcome. In order to evaluate telomerase activity in tumor tissue without radiolabeling the product, we developed a simple telomeric repeat amplification protocol-silver-staining assay that is less time-consuming, is safe and requires minimal equipment. In addition, we determined the sensitivity of the silver-staining method by using extracts of telomerase-positive thyroid carcinoma cell lines which were serially diluted from 5,000 to 10 cells. Telomerase activity was also assayed in 19 thyroid tumors, 2 normal controls and 27 bone marrow aspirates. The results indicate that the technique permits the detection of telomerase activity from 5000 to as few as 10 cells. We propose that it could be immediately applicable in many laboratories due to the minimal amount of equipment required

Molecular cytogenetics as a tools for predicting cancer prognosis with special reference to neuroblastoma tumors

Consistent cytogenetic abnormalities have been identified in a variety of human cancer cells and some of them are related to patiente prognosis. Fluorescence "in situ" hybridization (FISH) is a new methodology which can be used to detect cytogenetic anomalies within interphase cells. We present several aspects of FISH methodology and its application in several examples, including trisomy 8 detection with higt specificity and sensitivy in patients with myeloid leukemias; trisomy 12 detection with highter efficiency than conventional cytogenetics in patients with chronic lymphocytic leukemia; assessment of engraftment success; chimerism, and relapse in opposite sex bone marrow transplantation; and correlation of trisomy 7 with survival time in patients with prostate tumors. We discuss also some aspects of neuroblastoma tumors, one of the most frequent malignant solid tumor in childhood. At diagnosis the patient's age and tumor stage are the major prognostic factors. Favorable prognosis is associated with triploid karyotype, lack of 1 p abnormalities and absence of N-myc amplification, whereas unfavorable prognosis is associated with pseudodiploid or tetraploid karyotype, 1 p deletion and N-myc amplification. These abnormalities can be investigated quickly and effecctively in interphase cells using FISH.

Molecular cytogenetics as a tool for predicting cancer prognosis with special reference to neuroblastoma tumors

Consistent cytogenetic abnormalities have been identified in a variety of human cancer cells and some of them are related to patient prognosis. Fluorescence "in situ" hybridization (FISH) is a new methodology which can be used to detect cytogenetic anormalies within interphase cells. We present several aspects of FISH methodology and its application in several examples, including trisomy 8 detection with high specificity and sensitivity in patients with myeloid leukemias; trisomy 12 detection with higher efficiency than conventional cytogenetics in patients with chronic lymphocytic leukemia; assessment of engraftment success, chimerism, and relapse in opposite sex bone marrow transplantation; and correlation of trisomy 7 with survival time in patients with prostate tumors. We discuss also some aspects of neroblastoma tumors, one of the most frequent malignant solid tumor in childhood. At diagnosis the patient's age and tumor stage are the major prognostic factors. Favorable prognosis is associated with triploid karyotype, lack of 1p abnormalities and absence of N-myc amplication, whereas unfavorable prognosis is associated with pseudodiploid or tetraploid karyotype, 1p deletion and N-myc amplication. These abnormalities can be investigated quickly and effectively in interphase cells using FISH.