There is a recessive genetic condition that causes people to have blue tinted skin and purple lips, but because it is rare, it ordinarily isn't observed outside inbred communities such as one that existed in the early to mid-20th century in Eastern Kentucky in the Fugate family. These people were known as the Blue Fugates.
The Fugate family first settled in Kentucky in 1820. Martin Fugate and his wife Elizabeth Smith came to Troublesome Creek, an out-of-the-way region of Appalachia. According to some sources, Fugate was blue himself, though this has been disputed. Whatever his color, his offspring ended up with an unusual appearance: his son Zachariah was born with blue skin, and so were three more of their seven children. . . .
The Fugates had a genetic defect that resulted in a condition called methemoglobinemia, which means their blood didn't carry as much oxygen around the body. This makes the blood darker, which in turn causes the skin of white people to appear blue, and their lips to look purple. In addition, arterial blood looks chocolate brown rather than red. People with methemoglobinemia have higher levels of methemoglobin in their blood; they may have 10-20 percent, versus the average person's one percent. The Fugates' very blood was different from that of their neighbors. . . . Methemoglobinemia can cause developmental delay and seizures, but despite the intense appearance of their blue skin and purple lips, none of the Fugates suffered poor health or lived in pain. The condition had only a cosmetic effect, though the family endured psychological pain from their outsider status. Each of the Blue Fugates lived to a ripe old age. . . .
The conditions was particularly stigmatizing because it was understood to be connected with undue inbreeding (which was, in fact, present in the family).After interviewing the Fugates, Cawein concluded that their blood must be missing a crucial enzyme. To trigger the blood's natural processes, the doctor decided to inject the affected family members with methylene blue, a dye. The cosmetic results were nearly instant. Talking about the experience years later, Cawein said that the treated family members were thrilled to see the blue fade from their skin: "For the first time in their lives, they were pink." The solution really was that easy. The effects of the dye were temporary, but Cawein supplied the Fugates with methylene blue tablets to take every day.