The Human Genome Project, which has researchers worldwide mapping the genes of the human body, will likely change how medicine is practiced in the future. By understanding which genes control diseases such as cancer, Alzheimer’s and hypertension, physicians might someday be able to prevent diseases or reduce their effects by properly assessing and responding to genetic medical risks in advance.
“The project’s goal is to define a ‘parts list’ of what makes us human,” says Howard J. Jacob, PhD, Warren P. Knowles Professor of Human & Molecular Genetics and associate professor of physiology at the Medical College of Wisconsin. Dr. Howard is also director of the Human & Molecular Genetics Center at the Medical College. “Researchers are defining the chemical compounds of the genome and determining where specific genes are located on the chromosomes that make us human. Once we know the locations of the genes, we can then understand how the parts come together and function.”
The Human Genome Project officially began in 1990 as a 15-year program to characterize in detail the complete set of genetic instructions of humans and some important laboratory organisms. Progress on those original goals has been faster than expected – the first fully completed, highly accurate reference sequence of the human genome is expected by the end of 2003. Apart from the genome project, there are now a few laboratory tests to determine genetic risks for certain types of cancer and other diseases. However, treatments to address genetic risks are still years away.
Every cell in an individual’s body has the same genome, made up of an estimated 3.2 billion chemical units forming strings of DNA. Chromosomes, which carry hereditary information as genes, are made of DNA. There are about 40,000 genes coded within the cell’s DNA. Changes in the order of DNA units can increase an individual’s chance of developing an illness, protect against getting sick or predict the way he or she will react to medications.
Dr. Jacob compares the genome project to building an airplane with 40,000 parts and only a photo of an airplane to guide construction. Researchers have identified the function of about 5,000 of those genes to date. “At this point, we know how to build the wings, but we don’t know how to construct the engine or navigational tools that determine how the plane flies,“ he says. “When we can build the entire ‘plane,’ we’ll be able to provide individualized medicine.”
Today, medical treatments are largely based on studies of groups of patients, but what worked best on average for a group of people may not work best for an individual patient. Furthermore, diagnosis of some medical conditions is not exact enough to determine optimal treatment. There are several types of high blood pressure, for example, but it is sometimes difficult to make a specific diagnosis. As a result, multiple medications may have to be tried before the best results are achieved.
“When we understand which genes cause what disorders, we can provide a more exact diagnosis of a patient’s condition based on the genes he or she has,” Dr. Jacob says. “We can then prescribe a medication specifically for that individual determined by the genes he or she carries and the environment in which he or she lives.”
Medical College researchers are helping to define what specific genes do and how they participate in the disease process. Researchers utilize both human and animal experiments. Rodents, for example, are 90% identical to humans at the genetic level. Researchers at the Human & Molecular Genetics Center at the Medical College are investigating genetic causes of disorders such as cancer, diabetes, heart disease, high blood pressure, kidney disease, lung disease and sleep disorders. Funding comes in part from components of the Human Genome Project.
“In the short term, our research will help us better understand the disease process so that we can make better, more accurate diagnoses,” Dr. Jacob says. “In the long term, we will be able to provide individualized medicine, one patient at a time. Some day, each person’s entire genome will be known and we will be able to assess and address the individual’s risk for a disease long before symptoms appear.”
