POLG and cancer: Thus, to have information about the role of POLG1 germline variations in cancer predisposition, we chose E1143G (POLG1 polymerase domain) and two other T251I (POLG1 exonuclease domain) and P287L (POLG1 linker region) known POLG1 germline variants and created site-directed point mutations in POLG1 to achieve these point mutations [22].