MDC1 and male infertility: In line with the γH2AX-MDC1 interaction being fundamental for accumulation of DSB repair and signalling factors on chromatin in the vicinity of DSBs, H2AX and MDC1 knockout mice display similar phenotypes: growth retardation, male infertility, immune defects, chromosome instability and IR hypersensitivity at both the organism and cellular levels28,29.