It started with a headache that wouldn't go away.

Joanna Diaz found her way to a neurologist and underwent a battery of medical tests. Just before her 25th birthday, she learned she had epilepsy. Since then, she and her doctors worked to pinpoint the type of medication that would best suit her disease and her lifestyle, even her hopes for children.

"My drug is tailored to my needs," said Diaz, now 27, a senior at San Francisco State who will graduate in May with a political science degree. "It's a very comforting thing. I'll have to be on medication the rest of my life, so I want to choose ones that will fit my life. "

Diaz is enrolled in a study at UCSF focusing on epilepsy and genetics. It is part of a broader phenomenon known as personalized medicine, a scientific frontier that holds monumental promise by tailoring health care based on genetics. Through personalized medicine, diseases would be better understood and medical treatments would be customized based on genetic makeup.

Today a symposium is being held in San Francisco on the topic, also known as pharmacogenomics. And UCSF recently opened a center devoted to the emerging field. Under the Obama administration, personalized medicine is expected to make significant gains. While still in the U.S. Senate, Obama sponsored the Genomics and Personalized Medicine Act.

"Simply put, the study of genomics will help us learn why some people get sick and others do not, and use this information to better prevent and treat disease," Obama said when he introduced the bill in 2007. "We are just beginning to realize the full potential of this science to predict the onset of disease, diagnose earlier, and develop therapies that can treat or cure Americans from so many afflictions."

The legislation died, but many believe that with Obama now in the White House, personalized medicine will become a priority in national policy - in part because of its potential to help control health costs.

"It's very exciting, the idea of being able to treat people more individually," said Dr. Kathy Giacomini, a professor at UCSF in the school of pharmacy. "The idea of personalized medicine is to take genetic information and other factors - are you a woman, do you smoke, do you drink, do you have diabetes - and find out how you'd respond to a drug. Genetic factors can predict whether you are likely to respond to a drug or to have an adverse reaction."

Historically, drugs have been developed with a one-size-fits-all approach - yet that model clearly doesn't fit the entire patient population. Under personalized medicine, doctors will be able to better tailor drugs and medical treatment.

"Everyone has an individual genetic makeup, but we share patterns with other people which can determine how you'd react to certain drugs and treatment," says Dr. Kathryn A. Phillips, a professor of health economics and health services research at UCSF and director of the new center.

"Now there's a genetic test that will tell us which women with breast cancer will benefit from chemotherapy. It stratifies women into high, medium or low risk of recurrence. If they are at low risk, they might decide to forego chemotherapy. Before, everybody was lumped into one category."

Through personalized medicine, patients could learn how they'd fare with heart disease medications, or whether statins - cholesterol-lowering drugs - would work for them.

Genetic testing raises a host of ethical considerations - do we really want to know, for example, if we're going to get Alzheimer's?

"But drug response research is different," Giacomini said. "The whole purpose is to select a better drug, a better outcome."

Personalized medicine could also lead to better detection of diseases and earlier treatment.

That's a hope of Dr. Esteban Gonzalez Burchard, an associate professor at UCSF and lung specialist at San Francisco General Hospital. He is leading a genetic study on why some Latinos have disproportionately high rates of asthma.

"I find it amazing that our health is determined by where we're born and what family we're born into," said Burchard, who was born and raised in the Mission District - his mother was a migrant worker.

Isaura Casillas, a San Francisco resident whose two sons - Juan, 8, and Marvin, 9, - suffer from asthma, enrolled Marvin in the study in an effort to learn more about the genetic causes of asthma. She, too, has the respiratory illness, and so does her mother.

"Sometimes for me, it is very bad," she said. "Juan also gets very bad attacks. He stopped playing, running, and he really misses it. I want the doctors to learn a lot more."

Personal medicine

For more information on UCSF's new pharmacogenomics center, to go: