Assessment of Cytogenetic Abnormalities by FISH in Lymphocytes from a Victim Accidentally Exposed to Cobalt-60

Abstract

Background: A radiation accident occurred on 14 June 2011 in an industrial facility in Bulgaria whit Co source (137 TBq) used to sterilise equipment. Five people received doses exceed 1Gy and led to development of acute radiation syndrome. Biological dosimetry based on dicentric analysis was performed and the averaged acute whole-body doses estimated for the five patients were from 1.2 to 5.6 Gy. The purpose of this study was to evaluate in vivo induced chromosome aberrations four months after accident in the most severely exposed subject. Methods: Fluorescence plus Giemsa (FPG) staining and Fluorescent in situ hybridisation (FISH) were used to detect chromosomal aberrations in peripheral blood lymphocytes from the study subject four months after accidental exposure. FISH was provide using DNA probes specific for whole chromosomes #1, #4 and #11. Results: The mean frequency of dicentrics per cell ±SE was 0,425±0,042 determined by FPG. By FISH analysis the genomic frequency of apparently simple translocations (AST) per cell was 0,707±0,030. Incomplete translocations account for about 35%. For apparently simple dicentrics (ASD) the genomic frequency was calculated as 0,190±0,020. The frequency of complete plus incomplete dicentrics was 0,275 ± 0,020. Chromosome 1 was found to be involved in 52,35% of the total yield. Chromosome 4 was found to be involved in 30,2 % and chromosome 11 was involved in 22,82% of the total yield of translocations. Among 157 aberrant cells 28 cells or 17,83% were with one or more complex exchanges. Conclusions: This is a pilot study for a long time follow up assessing in vivo cytogenetic abnormalities in radiation accidentally exposed in Bulgaria persons. It is not possible at this to relate high frequency of translocation with long-term biological effect, but it is well known fact that ionizing radiation increase cancer risk in some individuals.