To date, a large volume of studies supports the notion that the γH2AX epigenetic biomarker has been established as the most sensitive and specific epigenetic biomarker for DSB detection and quantification. H2AX is a mammalian variant that belongs to the H2A histone family that has a phosphorylation site at a serine 139. This site becomes rapidly phosphorylated when DSBs are generated into DNA. It has been well documented that this phosphorylation is specific to DSBs . This specific phosphorylation is denoted as “γ-phosphorylation” and the H2AX histone molecules that “carry” this phosphorylation are designated as “γH2AX” accordingly.