Causes, Inheritance: Cancer gene types, Vogelstein clip 2
Professor Vogelstein, explains that cancer is in essence a genetic disease. But it's really quite different than all the other genetic diseases that people usually think of when they think about a genetic disease.
Bert Vogelstein, M.D. is a Howard Hughes Medical Institute Investigator and the Clayton Professor of Oncology and Pathology at Johns Hopkins University. His research focuses on the identification and characterization of genes that cause colon cancer. This has led to the discovery of the APC gene – the "gatekeeper" in colon cancer development.
Cancer is in essence a genetic disease. But it's really quite different than all the other genetic diseases that people usually think of when they think about a genetic disease. For instance cystic fibrosis: cystic fibrosis is always caused by a mutation in a single gene. People who get that mutation generally get very similar symptoms. One mutation gives you the disease. Cancer's not like that. No single mutation results in cancer. It's an accumulation of mutations in both these brakes and in the accelerators. You have to dismantle, basically, many of the controlling elements in the cell, to get to a cancer. If you just dismantle a few of them you might get a benign tumor, but you won't get a cancer. It's only when all of these pathways, or many of them, are inactivated that a cancer results. So it wouldn't be correct to say that a given mutation and a given gene causes cancer, what you can say is a given mutation contributes to the development of cancer.
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Professor Vogelstein explains that colon cancers provide a good example of a type of tumor in which the genetic steps leading from the normal colon epethelial cell to a cancer, are reasonably well known.
Familial colon cancer was long thought to be inherited; however a complete understanding of its causes awaited the discovery that specific genetic mutations confer a large increase in susceptibility to these types of cancers.
Professor Charles Sawyer explains that CML stands for chronic myeloid leukemia, which is a blood cancer and it is different from many cancers because it starts very slowly and patients when they're first diagnosed don't have many symptoms.