Having the prothrombin mutation increases the risk of developing a DVT (a blood clot in the deep veins, typically the legs) and/or PE (blood clot that travels to the lungs). DVTs are dangerous because they can damage the veins, leading to pain and swelling, and sometimes to disability.
Checksum is the general term. CRC is one kind of checksum. An FCS is. a checksum (typically a CRC) appended to a frame during serial data. transmission, so an FCS is one use of a praticular type of checksum. Some are better than others in detecting specific kinds of errors. Some are more easily computed in software or hardware.
1 Liver Enzymes: This is used to check the function of the live, due to the liver being a common organ for CRC to metastasize.  Tumor Markers: CRC cells can sometimes produce bi-products that are released into the bloodstream. Two examples of these are Carcinoembryonic Antigen (CEA and CA 19-9).