The majority of sporadic cases of colorectal cancers (up to 85%) display chromosomal instability (CIN), which manifests as aneuploid and polyploid karyotypes as well as multiple structural chromosomal changes such as translocations, allelic losses, amplifications and mutation of APC, and KRAS, the remainder of colorectal cancer patients (15%) demonstrate MSI [175,176]. The gene discussed is KRAS; the disease is colorectal cancer.