Massively parallel genetic sequencing systems offer much, but among the things they offer is large list of difficult questions, some of which were tackled in a Friday meeting on next-generation sequencing (NGS) systems. David Litwack, of the FDA's personalized medicine staff, ticked off a few concerns at the agency, including the fact that "we can't predefine what a test will find analytically." He said the biggest issue, in his view, is "the lack of a specific intended use" for such systems.