Blue people from Kentucky

I found an interesting article about the Fugate family who lived in Kentucky. It seems that they suffered from a genetic disease that caused them to have a distinctly bluish tint to their skin. The disease is called Methemoglobinemia and is caused by a deficiency of a particular enzyme. In its genetic form it is extremely rare. Both of your parents have to have a very rare recessive gene before you can inherit it. The Fugate family had the bad luck of having an ancestor, Martin Fugate, who carried the gene. Martin somehow managed to find a wife who also carried the gene. Then through excessive inbreeding amongst the local families in the hills of Kentucky, managed to spread the recessive gene to enough people that children began to be born with blue or purplish skin tones. In 1960 a doctor named Madison Cawein, heard about them and investigated. He discovered the enzyme deficiency and was actually able to temporarily "cure" several of the family members by simple injections.
I had never heard of this disease before reading the article, but I found out you can also get the disease through exposure to certain toxic chemicals.

Article on the Fugate family: THE BLUE PEOPLE OF TROUBLESOME CREEK
Wikipedia article on: Methemoglobinemia