Mutações Germinativas na Prole de Pessoas Expostas Ocupacionalmente à Radiação Ionizante de Césio-137.

Abstract

The radiological accident in Goiania in 1987, resulted in a serious episode of human contamination, animal, plant and environmental were exposed to cesium-137 chloride (137CsCl) that caused contamination and accidental and occupational exposure to ionizing radiation. Ionizing radiation is one of the environmental components that causes most cellular stress in complex organisms. Exposure to ionizing radiation induces breaks in nucleic acids, especially, DNA double and single strand breaks. Chromosomal microarray analysis is an important tool for the detection and microdeletion and microduplications in the genomes. In this study we proposed to analyze the effect of exposure to RI on the formation of CNVs in an exposed human population occupationally to ionizing radiation from Cesium-137 during the accident in Goiania. The exposed group consisted of 07 families, of which at least one parent was occupationally exposed to ionizing radiation from Cesium-137, including a total of 25 individuals, do not know the absorbed dose of the military who were occupationally exposed to ionizing radiation. 11 families with a group of individuals not exposed to IR was used as control were used including a total of 33 individuals with no history of exposure to RI. The genotyping microarray was conducted in CytoScan HD system (Affymetrix®) without then analyzes was performed in ChAS® software. The statistical tests used were: Shapiro-Wilk, Mann- Whitney U, Spearman correlation, discriminant function analysis, binomial test, χ2 test. All analyzes were performed using the statistical package SPSS 21.0, with a significance level of 5% (p <0.05). The frequency of CNVs were estimated loss - generation, gain - generation and burden - generation, representing 3,9x10-5, 6,8x10- 6 and 4,6x10-5 respectively for the exposed group. For the control group, the frequencies were 2,1x10-5, 5,9x10-6 and 3,1x10-5 respectively. Thus, the frequency of CNVs showed statistically significant differences between exposed and control groups using the Mann-Whitney U test. Thus, our data showed that CNVs are induced by IR exposure in a human population, while the losses were more frequent the gains in the exposed group. In addition, progeny from a population occupationally exposed to IR ~ 1.15x showed CNV more new than healthy controls. Therefore, with the present study was possible to validate the use of a high resolution method to describe a mutagenic exposure by IR signature, thus legitimized the use of CNVs as a useful biomarker to assess germline mutation military occupationally exposed to RI. In addition to validating the use of this marker, the study also pioneered research germline mutation in humans exposed to RI.