Premiering this Sunday on TLC is Dancer With Tiny Legs, a one-hour special that follows JoAnne Fluke — a spirited 34-year-old woman born with half a spine and the titular tiny legs — as she trains for her first “able-bodied” dance contest. It's the latest installment in what has become a flourishing full-fledged subgenre for TLC, Discovery Health, and a plethora of international news programs: medical-oddity documentary TV. The premise — an up-close look at the impossible and unbelievable in a sort of politically correct, modern-day sideshow kind of way — is simple and timeless. But a closer look at the subgenre reveals the world is maybe not that mysterious of a place: Most of these medical-oddity shows can fit snugly into one of six categories. Here they are.