It is interesting to see the topic of genetic mutation/flaws on the list
while I am studying this stuff is school!
 
From my understanding, the gene for Waardenburg is probably found where it
influences many different traits including the white stripe, ruby eyes, and
deafness.  A trait is defined as being any one characteristic and one gene
can effect many traits (pleiotropic).  This would explain why all of the
above traits are not necessarily found together all the time.
 
In genetics, there is no such thing as a flaw.  There is only the
expression of a gene in the phenotype (what you see).  Some traits may
be more desirable to us, but the fact that the trait persists means that
there may be something else that it effects that is good!
 
This set of traits is not a mutation.  A mutation is a process that happens
to cause a chromosome to have genetic material not present in either of the
two parents that gave rise to the mutated egg or sperm.  Since this set of
traits is passed from parent to child, it is present (perhaps unexpressed)
in one parent or both parents.  It is in the set of possible color patterns
for the offspring.  If a new color pattern emerges, like green, that could
be a possible mutation that expressed as a dominant allele (one of a set of
possible color patterns).
 
What I don't know is if the gene is dominant or recessive, this would only
be proved by breeding two ferrets affected by Waardenburg to each other.
If all of the kits have some expression of the disorder, it is probably
recessive, and if they do not, probably dominant.  If the two parents both
had two genes for Waardenburg and were bred to each other, the kits would
still have expression of these traits even if the gene was dominant.  This
type of experiment would be hard to do and would require an extensive
pedigree of all of the ferrets involved and the history of Waardenburg in
the lines.
 
I would argue that because of the prevelence of this set of traits in many
different species, the trait may have been around since the beginning of
mammals at all!  (Bob C.?)
 
Any (polite) comments or questions would be welcomed!
 
Rachel
[Posted in FML issue 2576]