In the F1 heterozygous mule, genes with mutations in DNA sequences were also highly concentrated in DNA replication (e.g., PRIM1, POLD2), DNA repair (e.g., PMS2 and MSH2), and cancer, such as proto-oncogenes (e.g., KRAS, HRAS) and tumor-suppressor genes (e.g., APC, PTEN). The gene discussed is PTEN; the disease is cancer.