In the summer of 1962, young Dr. Madison Cawain, a hematologist at the University of Kentucky's Lexington Medical Clinic, went to the Cumberland Plateau of eastern Kentucky to see if there really was, as rumor had it, a "race" of blue-skinned people--with real blue blood--living in remote villages. After several months of unsuccessful searching, two blue-skinned people showed up at the Perry Clinic in eastern Kentucky while Cawain was present. Cawain examined the couple and found no evidence of heart or lung disorders. He began to suspect methemoglobinemia, a condition wherein excess levels of methemoglobin, an inactive form of hemoglobin, accumulate in the blood and impart a blue color that masks the red of active hemoglobin. Methemoglobinemia can have several causes. One is genetic and results in a subnormal level of the enzyme diaphorase, which reconverts methemoglobin back into active hemoglobin. Cawain drew blood from several blue people, tested for the presence of diaphorase, and found none, thus explaining the buildup of methenoglobin and the signature blue color. The trait is a simple recessive. A person must carry both corresponding genes from each parent for the blue-blood condition to manifest. Someone carrying only one recessive gene won't show the blue blood/blue skin trait but can pass it on through generations. In the early 1800s, the Fugate and Smith families of Kentucky intermarried, and by strange chance, members of both families carried the recessive trait for methemoglobinemia, and blue-skinned children were born. They were robust, healthy, resistant to disease, and lived to envious old age. Following his treatment of the two blue-skinned people at the Perry clinic, Cawain visited five others with methenoglobinemia, and cured them by injecting them with methylene blue, a common tissue dye that acts in place of diaphorase. Within a few minutes, their skins had shed the blue color and become a normal pinkish.