Presentation on theme: " The Blue People of Kentucky A Study in Genetics: This is a colorized black and white photo of a family with some of the family members having blue skin."— Presentation transcript:
The Blue People of Kentucky A Study in Genetics: This is a colorized black and white photo of a family with some of the family members having blue skin. abcnews.com
Meet the Fugates… Martin Fugate had methemoglobinemia. He also had four children with the disorder.
Background info In normal blood hemoglobin is an abundant protein that carries oxygen. Some of the hemoglobin is in an altered form called methemoglobin. Methemoglobin carries almost no oxygen and in people with normal blood there is very little methemoglobin in their red blood cells. People with methemoglobinemia have too much methemoglobin in their blood which gives their skin a blue color.
methemoglobinemia People with this disorder have an enzyme that does not work normally. The enzyme, cytochrome b5 reductase, is responsible for changing methemoglobin into hemoglobin.cytochrome b5 reductase
The Fugates… Martin married a carrier of the disease in the early 1800s and they bore seven children; four of which were blue. The condition is inherited as a recessive trait and would appear most often in a small population. In this population they had methemoglobinemia, type I.
Geographic Isolation… The people of this community in Kentucky, Troublesome Creek were isolated from the rest of the country. When the town was settled there were no roads, making it hard to get out and people tended to intermarry. One of Martin’s sons married his maternal aunt and 100 years later Benjy Stacey was born (1975). He was blue at birth and doctors wanted to give him a transfusion until someone mentioned blue skin color ran in the family. His skin turned normal in a few days.
Geographic Isolation As railroads and development swept through, the blue Fugates started moving out of Troublesome Creek and marrying other people. The inherited blue began to disappear as the recessive gene spread to families where it is unlikely to be paired to a similar gene.
Methemoglobinemia There are several causes of methemoglobinemia. The most common is acquired by exposure to certain chemicals like benzene or certain antibiotics. It disappears when the chemicals are gone. The Fugates had an inherited form of the disease. Oddly enough, the treatment for the disease was a blue dye called methylene blue. When given a small dose the patients skin became normal.
Assignment We have identified methemoglobinemia as an autosomal recessive disorder. Go to the web site: http://omim.org http://omim.org This website, Online Mendelian Inheritance in Man, is a database with a wealth of information about genetic conditions. Follow your instructions on your worksheet.