Explain why molecular testing is essential not only in identifying disorders, such as cancer, but ...

Answer: Unlike inherited disease, in which every nucleated cell in the body contains defective DNA, cancer results when one cell acquires genetic defects that stimulate uncontrolled cell division and tumor formation. Virtually all cancers are thought to harbor genetic defects. The specific genes that are altered in tumorigenesis are oncogenes. Oncogenes can be detected at any point during the disease and when minimal residual disease (MRD) is present. MRD refers to small numbers of leukemic cells that remain in a patient during treatment or after treatment during remission. These small numbers of cells could lead to relapse of the cancer at a later time. This is why it is vital to monitor the progress of the cancers all throughout the course of the illness as well as after the disease is in remission.