There were also genes frequently mutated specifically in 1 or 2 of the evaluated groups, including MSH4, MDC1, WRN, and LIG1 in lung cancer, PALB2, BLM, and FANCA in breast cancer, RAD50, MSH3, MLH3, BLM, CLK2, and ERCC2 in liver tumors, MLH1, LIG1, TTK, and MSH2 in LI cancer, and MDC1 and POLD1 in skin cancer. The gene discussed is MDC1; the disease is breast cancer.