Identifying radiation responsive exon-regions of genes often used for biodosimetry and acute radiation syndrome prediction.

Gene expression (GE) analysis of FDXR, DDB2, WNT3 and POU2AF1 is a promising approach for identification of clinically relevant groups (unexposed, low- and high exposed) after radiological/nuclear events. However, results from international biodosimetry exercises have shown differences in dose estimates based on radiation-induced GE of the four genes. Also, differences in GE using next-generation-sequening (NGS) and validation with quantitative real-time polymerase chain reaction (qRT-PCR) was reported. These discrepancies could be caused by radiation-responsive differences among exons of the same gene. We performed GE analysis with qRT-PCR using TaqMan-assays covering all exon-regions of FDXR, DDB2, WNT3 and POU2AF1. Peripheral whole blood from three healthy donors was X-irradiated with 0, 0.5 and 4 Gy. After 24 and 48 h a dose-dependent up-regulation across almost all exon-regions for FDXR and DDB2 (4-42-fold) was found. A down-regulation for POU2AF1 (two- to threefold) and WNT3 (< sevenfold) at the 3'-end was found at 4 Gy irradiation only. Hence, this confirms our hypothesis for radiation-responsive exon-regions for WNT3 and POU2AF1, but not for FDXR and DDB2. Finally, we identified the most promising TaqMan-assays for FDXR (e.g. AR7DTG3, Hs00244586_m1), DDB2 (AR47X6H, Hs03044951_m1), WNT3 (Hs00902258_m1, Hs00902257_m1) and POU2AF1 (Hs01573370_g1, Hs01573371_m1) for biodosimetry purposes and acute radiation syndrome prediction, considering several criteria (detection limit, dose dependency, time persistency, inter-individual variability).