Hemoglobin is a large protein complex with iron containing heme groups attached. It gives red blood cells their color (why blood is red) and is responsible for transporting oxygen from the lungs to all the cells of the body. Each red blood cell contains around 270 million molecules of hemoglobin containing the iron atoms that bind reversibly with oxygen.
There is a special enzyme — diaphorase — that helps maintain the iron atoms in their normal molecular form. Without this enzyme activity, a blue type of hemoglobin — methemoglobin — can be formed in which the iron component has been compromised.
Methemoglobin can accumulate in the blood to a level that gives the skin a bluish hue. This condition is called methemoglobinemia and can be acquired in several ways. It can be caused by exposure to certain medicines, chemicals, or foods and it can be inherited when a child receives a rare mutant gene from each parent. People with this mutant gene can have blusish-tinted skin their whole life without any other symptoms. However, some may seek treatment for cosmetic reasons.
In 1820, a French orphan named Martin Fugate and his wife, Elizabeth Smith, moved onto the banks of Troublesome Creek located in the isolated and remote hills of the Appalachian Region of Kentucky. In an amazing coincidence and incalculable odds, both he and his wife carried a very rare recessive gene that when passed on to a child, left the child with the startling blue color of methemoglobinemia. They had seven children and four of them inherited the mutant gene from both of their parents and were various shades of blue in color.
The severity of the blue color varies and often is most notable in the lips and fingernails. Very high levels of blue skin can be life-threatening when accompanied by erratic heartbeat and circulatory problems.
The Fugates lived in a very isolated area and thus tended to marry close relatives. This kind of genetic isolation allowed for the continued reproduction and expression of the "blue skin" gene. Seven generations of the Fugates lived and reproduced in this remote area leaving many offspring with blue skin.
In the mildest form, methemoglobinema causes no harm, and most of the Fugates lived well into their 80s. Luna Fugate was one of the bluest Fugates known in the region. She was described as being blue all over with lips the color of a dark bruise. Despite her alien-like color, she was entirely healthy and had 13 children in her 84-year span of life.
Larrie Stone is a retired Dana College science professor.