Quadruple helix DNA found in living human cells — and it may be linked to cancer

The double helix DNA structure is about as iconic as its gets. But geneticists have long speculated about the potential for a quadruple helix to exist — a four-stranded DNA structure. And indeed, computer models and lab experiments have suggested that it's theoretically possible. » 1/21/13 8:00am 1/21/13 8:00am