Using DNA sequencing, scientists at Washington University in St. Louis were able to identify the complete DNA sequence of a cancer patient. The researchers used cells donated by a woman in her 50s who died of acute myelogenous leukemia; they mapped all the genes in her tumor cells and compared them with the genes from a normal cell. The researchers found changes present in genes of her leukemia, but not in the genes of her skin.

The Washington team identified 10 gene mutations that were associated with that type of cancer. An interesting finding was that almost all the cells in the tumor sample had nine of the gene mutations. One of the newly discovered abnormal genes blocks chemotherapy drugs from ever getting inside the cancer cells to kill them.

Just two of the identified genetic alterations were associated with this form of cancer before. Eight were new genetic mutations that were never linked to this kind of cancer before.

Leukemia has long been the subject of numerous studies and experiments; up to this point, however, the results haven’t been that good. Scientists hope this new genetic cancer "code" will help develop more targeted drugs in the future, improving the existing cancer medications. Each year in the United States, nearly 8,800 people die of AML, a disease that affects blood and bone marrow.

"This is the first human cancer genome that's been sequenced. In the past, we've always looked at parts of the genome for mutations. But this is the first time that we've been able to look at everything," said Dr. Timothy Ley, who led the study.

Researchers are now trying to identify all the genetic mutations that cause lung, brain and ovarian cancers, in an attempt to find which genetic alterations cause which cancers. "There are probably many, many ways to mutate a small number of genes to get the same result, and we're only looking at the tip of the iceberg in terms of identifying the combinations of genetic mutations that can lead to AML," study senior author Richard K. Wilson, director of the Washington University Genome Sequencing Center, said in a statement. He said he hoped scientists would be able to come to perform DNA sequencing by using only a drop of blood that would be analyzed by a computer.

The study, conducted at Washington University in St. Louis, was published Wednesday in the journal Nature.