Estudo do cariotipo constitucional e dos tecidos envolvidos na lesão de crianças portadoras de defeito do tubo neural (DTN) por meio de analise citogenetica convencional e FISH

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The association between chromosomal abnormalities, specially aneuploidies and neural tube defects (NTDs) is well known, principally when NTD is not the only malformation present. Recently, research in animal models, using fluorescence in situ hybridization (FISH) identified aneuploidy in neural tissues. The aims of this work were to identify the frequency of chromosomal abnormalities in NTDs fetuses and newborns and the possible association of them restricted to cérebro-vascular (CV) tissue. For the detection of aneuploidy conventional cytogenetic studies on lymphocytes and CV tissue and interphase FISH of CV tissue utilizing alfa-centromeric probes of 18 chromosomes (FISH-Multiprobe/Cytocell) were performed. In order to establish the confidence interval of the diploid signals the interphase FISH analysis was performed in 10 control individuals, showing mean near to 100%. Forty one NTDs cases were evaluated and separated into three groups, according to the collected samples and their analysis. Group 1: karyotype from lymphocytes and CV tissue and FISH analysis from both, 13 cases. Group 2: karyotype from CV tissue, 5 cases. Group 3: karyotype from lymphocytes, 23 cases. In group 1, 4 (31,0%) presented abnormal karyotypes restricted to CV tissue: mos 92,XXYY/46,XY, mos92,XXXX/46,XY on spina bifida and monossomy of the chromosome 6 in mosaic on anencephaly. The frequency of chromosomic anomalies in that study was of 6%. A larger percentage of restricted aneuploidies on CV tissue was observed. The aneuploidies percentage found in this tissue was of 15% when studied by conventional cytogenetics and of 25% when analyzed by FISH. In group 2, all samples presented normal karyotypes. In group 3, two cases of anencephaly presented abnormal karyotype: chi47,XY,+21/46,XX and mos92,XXYY/46,XY and two cases presented heteromorphisms 46,XY,inv9(qh) (spina bifida ) and 46,XX,21ps+ (encephalocele). There is a greater proportion of aneuploidy restricted to CV tissue. The percentage observed in that tissue was 25%, similar to neural tissues of rodents in experimental studies (33%). These results suggest that numeric anomalies can be very common in tissue involved with NTD. However, these results suggest that further studies with neural tissue in humans are fundamental to explain the relationship between chromosomic anomaly and nervous tissue

ASSUNTO(S)

anormalidades sistema nervoso aneuploidia tecido nervoso mosaicismo defeito do tubo neural

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