Table 1.

Summary of key messages per section and presentation.

Section	Presenter	Key messages
Biodosimetry
	C. Badie	1. In a large scale event, high-throughput measurements are required for individual dose estimation for radiobiological triage
		2. New sequencing technology: nanopore sequencing to detect radiation-responsive genes in human peripheral blood: portable, rapid, real-time biodosimetry platform
		3. Identification of specific FDXR transcript variants responsive to ionizing radiation (IR) –>in vivo validation in blood of radiotherapy patients
		4. High responsiveness of FDXR-201 and FDXR-208
		5. New class of gene based radiation exposure markers: FDXR-218 and FDXR-219 without endogenous expression, but a clear detection after IR
	B. Terbrueggen	see below
	S. Amundson	1. Development of algorithms to allow translation between animal and human responses, and between in vitro and in vivo responses
		2. Exposure modalities relevant for anticipating exposure scenarios: impact of relevant exposure factors such as dose rate, presence of neutrons, or exposure to internal emitters
		3. Gene expression (GE) approach shows great promise for dose reconstruction and injury prediction
		4. Better understanding and integration of factors that may impact both an individual’s physiological response to radiation and their GE response still needed
	P. Ostheim	1. GE changes in the peripheral blood (mRNA and miRNA) provide indications of the exposure pattern and a suggestion of the percentage of the exposed body area
		2. Dose-dependent GE responses to incorporated radionuclides (223Ra)
	P. Rogan	1. GE signatures for radiation exposure are susceptible to nonspecific changes caused by common, confounding hematological disorders
			2. Strategy: necessity to identify and mitigate confounder up front, include confounders as controls, exclude genes responsible for false positive calls
	A. Evans	1. Transcriptional biomarker can be used for assessing internalized 131I –>differentiate exposed from unexposed
		2. Dose and time dependent GE signature for internalized 131I over a period of 15 days after exposure
	D. Bazyka	1. Examination of 314 Chernobyl cleanup workers, and staff of the ‘Shelter’ and exclusion zone with various doses of external irradiation
		2. Demonstration of a dose–response relationship on a molecular level with promising results for biological dosimetry
	S. Ghandhi	Examination of molecular response to internal radiation using mice injected with 137Cs –>sustained impact of dose and low dose-rate on immune response
Effect prediction
	P. Ostheim	1. Dose estimates are a ‘surrogate’ for prediction of acute health effects
		2. Concept of radiation-related biomarkers for effect prediction: integration of multiple radiation exposure characteristics as well as cell- and molecular-based processes like individual radiosensitivity via molecular changes lying downstream of the exposure and upstream of the effect
		3. Integrative approach for more robust and simplified prediction of later occurring acute health effects
	M. Gomolka	1. A radiation specific gene signature was identified in uranium workers 20–30 years after exposure
		2. Low and high dose exposure groups of uranium workers can by distinguished by gene expression analysis
		3. Deregulated genes are involved in immune response pathways, including interferon and pro-inflammatory responses
High-throughput and point-of-care (POC) diagnostics
	B. Terbrueggen	1. REDI-Dx: high throughput and blood-based biodosimetry test system
			2. Measurement of radiation responsive mRNA transcripts for estimation of absorbed radiation dose, extremely low false positive rate
			3. Up to 1200 samples within 24 hours and first results are available after 6.5 hours
			4. Only biodosimetry test for which the performance has been validated
	F. Zenhausern	1. Advances of paper-based vertical flow multiplex assay system (VeriFAST) for rapid biodosimetry in a mobile environment
		2. Simple user interface for self-collection and testing on a low-cost basis
		3. High sensitivity for a variety of nucleic acids to proteins multiplex panels of biosignatures for different bioeffects
		4. Future work and validation needed
	C. Badie	Nanopore sequencing: portable, real-time and high-throughput biodosimetry platform for assessing radiation exposure (see above)
	P. Ostheim	1. Current progress in the development of point-of-care device based on microfluidic technology as a stand-alone platform
		2. Limitations in the linearity of GE values miniaturization restrictions have to be overcome
Low-level radiation
	L. Kaatsch	1. Diagnostic and interventional radiology provides alternative exposure model for LLR experiments, here computed tomography
		2. Modern CT diagnostics evoke genotoxic alterations with deregulation of well-known genomic biomarkers and DNA damage
		3. No increased biological effectiveness of varying X-ray spectra in dual-energy CT
	G. Woloschak	1. Irradiated animals tissue archive hosted at Northwestern University: repository of samples and data collected in the course of large-scale animal studies –>samples and existing datasets available upon request (janus.northwestern.edu)
		2. Difficult to do an analysis for the animals with very low dose rates 3. Mostly paraffin embedded tissue of differing quality, mRNA measurements challenging and miRNA measurements promising
Methods
	P. Ostheim	1. Saliva, as a noninvasive easily accessible biofluid, contains presumably RNA biomarkers for prediction and diagnosis of several diseases and is poorly characterized for radiation biodosimetry
		2. Identification of challenges (high yield of bacterial RNA and low yield of human mRNA) and development of a robust methodology to process human whole saliva for GE analysis
		3. Next step: saliva samples from radiotherapy patients used to evaluate the applicability of this workflow for GE analysis for its use in a radiobiological context
	R. Ullmann	Introduction of a novel RNASeq analysis strategy for whole genome exon- and not gene-based GE screens: rapid, budget-friendly and reproducible
	S. Schüle	1. Discrepancies in baseline and height of radiation-induced differential GE of commonly used radiation-induced genes have been observed among laboratories and in the validation of GE NGS data (gene-based examination) using qRT-PCR (exon-based examination).
		2. Identifying radiation responsive exons and primer-probe designs of genes widely used for biodosimetry and ARS prediction
		3. More meaningful comparison of NGS and qRT-PCR measurements (both exon-based)
	M. Riego	Alternative transcript or splicing variants of known radiation-responsive genes can be used as a potential source of individually variable response to certain radiation qualities at an exon-level

The table is ordered per main section of the key session ‘Gene expression for biodosimetry and effect prediction purposes: promise, pitfalls and future directions’ at ConRad 2021 as well as presenters. It summarizes the key contents of each presentation. Details are provided in the text of the manuscript.