Download Blue People of Kentucky Investigating a Human Genetic Trait The

Blue People of Kentucky Investigating a Human Genetic Trait
The hills of Kentucky are dark and mysterious. Few outsiders travel through them. Families have lived
there for generations, keeping the pioneering spirit alive In log cabins that they built with their own
hands,
Rumors about such places are easily started. "There are blue-skinned people who are living in
Troublesome Creek" might sound like a rumor. But. in fact. there are blue-skinned people living in
Troublesome Creek! They have been there for more than 150 years.
Finding the Cause 0f Blue Skin
In the mid-1960's, Doctor Madison Cawein heard stories about people "as blue as indgo" living in
the Kentucky hills. Doctor Cawein is a hematologist (heeTAHL-uhi.-jihst), a doctor who treats blood
disorders. He investigated the story and found people whose skin was blue but who were normal and
healthy in all other ways. The cause of their blue skin color was a mystery. Doctor Cawein predicted that
it had something to do with their blood. But blood samples taken from several blue people showed that
their blood was normal.
Further investigation showed that blue skin could be traced to one family. the Fugate’s. In fact,
the first-known blue person of Troublesome Creek was Martin Fugate. who came to Troublesome Creek
in 1820. Four of his seven children had blue skin. Over the generations, the Fugate’s married into other
families, and the blue trait was passed on. The pattern of the trait's appearance convinced Doctor
Cawein that blue skin is a genetic trait that is inherited through recessive genes. Martin Fugate's wife,
Elizabeth, did not have blue skin, but she is thought to have carried a recessive allele for the trait.
Doctor Cawein knew about an inherited condition called methemoglobinemia (meht-HEE-muh-glohbuh-nee-mee-uh). Methemoglobinemia had been studied in Eskimos and Native Americans in Alaska by
Doctor E. M. Scott. In this condition, a protein, methemoglobin, collects in the blood and causes a
person's skin to appear blue. Hemoglobin, the oxygen and carbon-dioxide-carrying protein found in red
blood cells, is slowly converted to methemoglobin, But in normal red blood cells, an enzyme called
diaphorase (di-AH-for-ayz) converts methemoglobin back to hemoglobin. Doctor Cawein hypothesized
that there was a deficiency of diaphorase in people with methemoglobinemia He also predicted that the
blue people of Troublesome Creek had methemoglobinemia.
To test his hypothesis, Cawein took blood samples from several blue people and tested them for
diaphorase. He found none. Instead, he found that the red blood cells were full of methemoglobin. His
hypothesis was correct. Martin Fugate had had methemoglobinemia, and he had passed it on to his
descendants.
QUESTIONS
1. Were Denmon and Dempson identical twins or fraternal twins?_____________
2. How can you tell? _______________________________________________
______________________________________________________________
3. Write in the genotypes of all the individuals using the symbols:
 NN= normal hemoglobin
 Nn = heterozygous for normal hemoglobin
 nn = methyhemoglobemia (blue skin)
4. How is it possible. if there were no blue people in one whole generation. that the blue skinned characteristic showed up again in the children of Greet and Aneliza?
5. What relationship are Greet and Aneliza?
6. If they had another child, what is th'3 probability of it having blue skin?