Table 2.

Principal of features of DNA damage-associated biomarkers

Biomarkers	Advantages	Limitations	Readout/time of onset	Cell types
Cytogenetic (e.g. micronuclei, translocations, dicentrics)	Standardized protocol and relatively low costs High specificity to IR and low background in non-exposed population (dicentrics) Easy identification (micronuclei) Can be used in cases of long-term IR (translocations)	Laborious, time-consuming, sophisticated, variability in scoring cells Limited sensitivity at dose <0.1 Gy High background frequency (translocation and micronuclei)	Days to weeks Retrospective (translocations)	WB PBMC
Proteomic (e.g. γ-H2AX, pATM, pP53)	Highly sensitive and linear with radiation dose : 0.01–8 Gy Can detect radiosensitive individuals Potentially high-throughput analysis	Not specific to IR (also formed in response to UV and other genotoxins) Fast decline of the signal Variation of foci frequency between individuals	Minutes to days	PBMC Fibroblasts
Genomic (e.g. mRNA, SNPs)	High-throughput analysis Linearly dose dependent to IR	Bioinformatic challenge and high cost (RNA-Seq)	1–3 days	PBMC WB Cell lines
Epigenomic (e.g. miRNA, lncRNA)	Relatively stable Potentially high-throughput analysis Cell- or tissue-type-specific expression	Lack of data on specificity and sensitivity	Hours to days	Serum PBMC Cell lines

WB, whole blood; PBMC, peripheral blood mononuclear cell; IR, ionizing radiation; UV, ultraviolet; ATM, ataxia-telangiectasia mutated; lncRNA, long non-coding RNA; miRNA, microRNA; p, phosphate group; p53, tumour protein p53; SNPs, single nucleotide polymorphisms.