Elizabeth Holmes, whose Theranos blood testing company was valued at $9 billion last year, is the world's youngest female billionaire. Her uncle died from cancer because it wasn't caught early, motivating Holmes to develop a way to potentially detect diseases earlier. She dropped out of Stanford U. her sophomore year to launch blood testing firm Theranos in 2003. Faster, cheaper and less painful than other tests, it can quickly test a drop of blood at a fraction of the price of commercial labs, and can run up to 70 different tests. In 2013, Walgreens, the largest U.S. retail pharmacy chain, announced plans to roll out Theranos Wellness Centers inside its pharmacies. So far, there are 41 Theranos labs in California and Arizona. Holmes was instrumental in passing a law in Arizona this past April that allows patients to get a blood test without a doctor's order, a requirement in other states. Some scientists have questioned the performance of Theranos tests compared to other labs, because Holmes hasn't published large peer-reviewed studies. To evaluate the accuracy of its tests, the company says it took the unusual step (labs are not required to do so) of submitting its technology to the Food and Drug Administration. Customers including Pfizer, Cleveland Clinic, and the U.S. military are not deterred. Board members include elder statesmen George Shultz and Henry Kissinger.