While somewhat light on science, the recent New York Times Magazine cover story “The Hazards of Growing Up Painlessly” is a fascinating profile of Ashlyn Blocker, a girl who suffers from a rare, harrowing, and little-understood condition known as “congenital insensitivity to pain.” Although not mentioned in the article, one of the only other diseases that rob patients of the ability to feel pain is leprosy. Although the stereotype persists that leprosy makes parts of your body fall off, what actually happens is that nerve damage from the Mycobacterium leprae causes the extremities to lose sensation and then atrophy. The inability to feel pain leads to chronic sores, gangrene, blindness, and destruction of flesh. Continued bruising, without sensation of pain, can result in absorption of bone, which is responsible for the foreshortening of leprosy patients’ fingers and toes. Only if you are diagnosed with leprosy and treated quickly with a cocktail of powerful antibiotics and steroids can you be cured and stave off the worst of the damage. But at least there is a cure for leprosy, which is more than can be said for the genetic mutation that makes day-to-day living for patients like Ashlyn so complicated.