Cathy and Charles Fitch of Mount Pleasant are enjoying life as he is in remission from leukemia. Doctors have based treatments based on Charles' genome since his diagnosis in June 2011. David Quick/Staff
Genomic sequencing 101
Nearly every cell in the human body, from the ones in the fingernails to the ones deep inside the brain, contains a complete set of DNA, the operating instructions that influence everything from a person's hair color to susceptibility to disease.
For years, doctors have been able to test specific genes to detect the presence of mutations associated with disorders such as cystic fibrosis and sickle cell disease.
But only recently have scientists been able to map out a person's entire genetic code, or genome, by sequencing all 25,000 or so genes in one fell swoop.
How many have the potential to cause cancer? Dr. Stephen Ethier, chairman of breast cancer research at the Medical University of South Carolina says, "We're still searching for the final answer, but it's probably a few hundred genes. Some we know well. Most we still don't."
To sequence a person's genome, doctors need to collect less than a teaspoon of blood or saliva. Then chemicals are used from this sample to break open the cell membranes and gather the DNA that had been housed inside them. Enzymes strip away surrounding proteins to isolate a clump of tiny, whitish strands of DNA. That genetic material is placed in sophisticated machines that "read" each of the 3 billion base pairs that make up a person's genetic code.
Sequencing a genome used to take a year. Now, it can be done in a day.
Air Force veteran Charles Fitch is alive today, most likely because of "personalized" cancer treatment that used to be the stuff of science fiction, all thanks to cancer research and treatment based on genomics.
Genes vs. genome
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MUSC using genetic mapping for research and personalized treatment of cancer