Medical Genetics When irradiation occurs during the Go/G1 phase of the cell cycle large-scale rearrangements appear as exchange-type chromosome a berrations at the next mitosis, such aberrations can alter cellular phenotypes, and are important in various areas of biologyMedical Genetics When irradiation occurs during the G0/G1 phase of the cell cycle, large-scale rearrangements appear as exchange-type chromosome aberrations at the next mitosis. Such aberrations can alter cellular phenotypes, and are important in various areas of biology: