personalized_medicine_01_txt

Improved diagnosis of disease is another benefit of personalized medicine.  The first example of great success was the ability to divide the disease B-cell lymphoma into two different diseases based on patterns of gene expression displayed by the cancer cells.  By having the sequence of the human genome and knowing what genes are present in human DNA, researchers were able to produce a “gene chip”—a glass slide that has a test for every gene in the genome on it.  The researchers could then ask which genes, which of those 22,000 instructions in the DNA, were actually used to produce a particular tissue—in this case a B-cell in the blood. They were able to compare the genetic instructions used in normal B-cells to those used in B-cells in patients with leukemia.  It turns out that there are some key differences in the instructions, or genes, used in the disease.  Those differences in gene expression can be used to diagnose the disease.  Using this approach, two distinct gene expression signatures were observed in different leukemia patients, leading to the conclusion that rather than being a single disease, the patients with different signatures had different diseases.