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    Padronização do teste de arranjos de polimorfismos de nucleotídeos únicos (SNPa) para a detecção de anormalidades genético-moleculares em leucemia mieloide aguda e síndromes mielodisplásicas
    (Universidade Federal de São Paulo (UNIFESP), 2014-09-26) Noronha, Thiago Rodrigo de [UNIFESP]; Chauffaille, Maria de Lourdes Lopes Ferrari Chauffaille [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Introduction: Single nucleotide polymorphism array (SNPa) is a type of DNA microarray which is used to detect polymorphisms within a population. SNP is a variation of a single nucleotide in a DNA sequence, and is the most frequent type of variation in the genome. Millions of SNPs have been identified and a map of SNPs can be used as an excellent genotypic marker for research. SNPa has been widely used in cancer genetics due to its great performance in providing information of copy number variation (CNV) and copy neutral loss of heterozygosity (CN-LOH). In Onco-hematology, AML/MDS provide an interesting model for investigation of new molecular changes by SNPa with implications for pathogeneses of diseases. This is evidenced by the lack of cytogenetic abnormalities in cases of AML/MDS and general lack of molecular assays that can be used to detect such abnormalities. Objectives: The objectives of this study were to standardize the SNPa method in AML and MDS, and to establish the similarities and differences between SNPa and karyotype. Materials and Methods: 25 patients diagnosed with AML (n=22) and MDS (n = 3) were studied. The G-banding karyotype according to usual method and SNPa (Cytoscan HD - Affymetrix) were performed using DNA extracted from mononuclear cells from bone marrow (BM) and from buccal cells (BC). Results: The mean age of the patients studied was 54 years old, and the median age, 55 years (range from 28 – 93). 12 (48%) were male and 13 (52%) female. 10 patients showed abnormal karyotype (40,0%), 11 normal (44,0%) and 4 had no mitosis (16,0%). Regarding the BM SNPa: 17 were abnormal (68.0%) and 8 were normal (32.0%). Comparing the karyotype with SNPa from the 25 cases, by karyotype was possible to detect a total of 17 alterations (deletions/loss: 8, trissomy/gain: 7 and translocation: 2) and by SNPa a total of 42 alterations (loss: 17, gain: 16 and CN-LOH: 9). Conclusion: It was possible to standardize SNPa in AML/MDS and compare it with the abnormalities detected by karyotype. SNPa increased the detection rate of abnormalities compared to the karyotype. It was possible to confirm that it is a reliable and sensitive instrument for detecting submicroscopic and CN-LOH changes. SNPa also offered a new set of abnormalities that deserve to be further investigated in future studies.