This reminded of an article I once read, _The Blue People of Troublesome
Creek_, by Cathy Trost, which appeared in the magazine _Science 82_,
November, 1982, page 34.  This article described the "blue Fugates", a
family that lives in Kentucky, and many members of which are, well, blue.
Really blue.  So blue that doctors go nuts whenever one of them walks into a
hospital or clinic for anything.
 
A hematologist, Madison Cawein, eventually figured out that it was
methemoglobinemia, a rare hereditary blood disorder that results in excess
levels of methemoglobin in the blood.  Methemoglobin (which is blue) is a
non-funtional form of the normal hemoglobin which carries oxygen (and is
red).  In most people, normal hemoglobin is converted to methemoglobin at a
very slow rate, and the enzyme diaphorase converts it back.  The blue
people, however, were lacking the converting enzyme.  Cawein tried an
injection of methylene blue, which acts as an electron donor (which is
another way to convert the methemoglobin to hemoglobin), and people turned
normal pink within a few minutes.  Nowadays, they just take methylene blue
pills.  Cawein published his report in the _Archives of Internal Medicine_
in 1964.
 
It turned out that the "disorder" (the people are otherwise extremely
healthy) began in the 1920's when a French settler arrived (family history
had it he was blue), and married a woman who must have been also carrying
the recessive gene.  Since the railway didn't come in until 1912, and local
roads took another 30-40 years to lay down, the people were forced to
intermarry, resulting in quite a few with both recessive alleles.  Nowadays,
as they marry out, the trait is disappearing, although some of the babies
are blue for a few weeks after birth.  It seems that newborns have lower
amounts of diaphorase, and so they may appear blue for a short time, even if
they only have one recessive allele.
 
Yes, I suspect that these blue ferrets are due to something similar, but
hormonally triggered.  Probably they lose their diaphorase for a time after
mating.  Hormones are pretty powerful substances.
 
MAnon
[Posted in FML issue 1407]