I know it's not nice to make fun of people from "the hills of eastern Kentucky" (I'm from the hills of eastern Georgia, so there's a pot-kettle dynamic), but the Kircher Society does it in such an interesting way:
Sometime around 1820, a French orphan named Martin Fugate, carrier of an incredibly rare recessive gene for a disease known as hereditary methemoglobinemia, settled on the banks of Troublesome Creek in Eastern Kentucky and married Elizabeth Smith, carrier of the same incredibly rare recessive gene. It was a remarkable coincidence with a bizarre result: Four of the seven Fugate children were born with bright blue skin that lasted their entire lives. ... The reason for this strange skin disorder was only discovered a century later when it was realized that due to an enzyme deficiency, the Fugates' blood had a diminished oxygen-carrying capacity. Over the years, the Fugates interbred repeatedly. Blue people proliferated. Six generations later, according to a Science article published in 1982, there were still Blue Fugates roaming the hills of Eastern Kentucky.
It could be worse: The Fugates could have been "blueberry muffin babies," which you can read about after the jump.
As you'll learn in our upcoming "mental_floss presents: Med School in a Box:"
Blueberry muffin babies sound adorable, like something that might be friends with Strawberry Shortcake or the Little Twin Stars. In fact, these unfortunate infants are infected since before birth with cytomegalovirus. Rupturing of red blood cells leads to production of bilirubin, a byproduct of hemoglobin metabolism. This bilirubin accumulates in the skin and causes the yellow discoloration known as jaundice. At the same time, bleeding in the skin causes splotches called purpura. The resulting yellow babies with purple spots evidently reminded some cold-hearted individual of a breakfast treat.