Holmes gained widespread media attention roughly a decade ago as a rare young female start-up founder who was defying the odds. She claimed to run hundreds of tests on mini lab machines with just a few drops of blood. Her signature look included black turtlenecks in the style of Steve Jobs, she spoke in a low voice and she wowed audiences with presentations on the company’s ambitions. She founded the company as a college student at Stanford University, then dropped out to propel the company to a peak valuation of roughly $900 million in a storied Silicon Valley office building employing hundreds of people.