Around 1820, a man named Martin Fugate settled near Hazard, Kentucky. As their settlement is a remote rural area, his family and the other families there intermarried. Martin Fugate’s wife, Elizabeth Smith, was a carrier of methemoglobinemia, so was the family that the Fugates intermarried with. This resulted in their descendants inheriting the gene that caused blue skin. During the 20th century, nurse Ruth Pendergrass and hematologist Madison Cawein III studied the condition. Cawein treated the family with methylene blue, which reduced their symptoms and blue color. Benjamin Stacy, born in 1975, was the last known descendant wth the gene as the family began to spread out with better access to travel.