Abstract
We aimed to estimate the rate of germline mutations in the offspring of individuals accidentally exposed to Cesium-137 ionizing radiation. The study included two distinct groups: one of cases, consisting of males and females accidentally exposed to low doses of ionizing radiation of Cs137, and a control group of non-exposed participants. The cases included 37 people representing 11 families and 15 children conceived after the accident. Exposed families incurred radiation absorbed doses in the range of 0.2 to 0.5 Gray. The control group included 15 families and 15 children also conceived after 1987 in Goiânia with no history of radiation exposure. DNA samples from peripheral blood were analyzed with the Affymetrix GeneChip® CytoScanHD™ to estimate point mutations in autosomal SNPs. A set of scripts previously developed was used to detect de novo mutations by comparing parent and offspring genotypes at the level of each SNP marker. Overall numbers of observed Mendelian deviations were statistically significant between the exposed and control groups. Our retrospective transgenerational DNA analysis showed a 44.0% increase in the burden of SNP mutations in the offspring of cases when compared to controls, based on the average of MFMD for the two groups. Parent-of-origin and type of nucleotide substitution were also inferred. This proved useful in a retrospective estimation of the rate of de novo germline mutations in a human population accidentally exposed to low doses of radiation from Cesium-137. Our results suggested that observed burden of germline mutations identified in offspring was a potentially useful biomarker of effect to estimate parental exposure to low doses of IR and could become an important marker suitable for biomonitoring human population exposed to environmental mutagens.
Highlights
In 1987, a series of unexpected events resulted in a major radiological accident in Goiania, Goias, Brazil, causing human, animal, plant and environmental exposure to gamma ray ionizing radiation (IR) of Cesium-137 and contamination by the radionuclide [1]
The current study used SNP genotypes from a cohort of offspring born to parents accidentally exposed to Cs-137 to estimate the induction of germline mutations in humans exposed to low doses of ionizing radiation
This study pioneered the analysis of Mendelian deviations (MD) using autosomal SNP data observed in parent-offspring trios as biomarkers of effect to low doses of ionizing radiation
Summary
In 1987, a series of unexpected events resulted in a major radiological accident in Goiania, Goias, Brazil, causing human, animal, plant and environmental exposure to gamma ray ionizing radiation (IR) of Cesium-137 and contamination by the radionuclide [1]. Individual exposure resulted from internal and external contamination by the radioactive salt, while others were exposed to radiation emitted by the decay of Cesium-137. People were both exposed to radiation and contaminated by the radionuclide. 249 people were exposed to IR from Cesium-137, leading to individual absorbed doses of IR ranging from 0 to 7 Gy, resulting in four fatalities during the acute phase of the accident [2, 3]
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