From:
Sukie Crandall
Date: 2010-04-14 16:51:34 UTC
Subject: [ferrethealth] Re: [Ferret-Genetics] Genetics of silvers
To: fg <Ferret-Genetics@yahoogroups.com>, fhl <ferrethealth@yahoogroups.com>
I'm replying specifically for silver mitts since the conversation has
taken that turn.
In our case, so far every ferret we haver had with complete silver
mitts as a kit (except for one who is only 5 years old) has wound up
with cardiomyopathy, BUT the numbers are small but that could be
nothing more than coincidence, but maybe not as you see.
Now, Dr. Brett Middleton, genetics professor, DID wonder if that
marking type (where the dark bib and dark socks are completely
replaced by white) might be at least one different form of neural
crest variation than the more usual forms (different genetics), and
some forms of neural crest genetic variations are very well documented
to cause increased rates of cardiomyopathy in multiple species though
I don't know if that has been looked at in ferrets, yet.
One thing to note is that sometimes there can be different genetic
causes across individuals for some neural crest variation markings.
There are things which are most likely, such as K.I.T. genetics for
the splotchy ones with body markings -- as per past post by
geneticist, Dr. Brett Middleton -- so often seen in the U.S. but there
could easily be multiple types of neural crest genetics seen in
ferrets. For example, in relation to a ferret with neural crest
genetic variation markings and many more typical neural crest markings
who I've privately discussed with someone, there also is
microoophthalmia. Microophthalmia is sometimes it's own problem
though microophthalmia transcription factor genetic problems can be
seen with Waardenburg (Most causes of neural crest genetic problems
in ferrets appear to involve the KIT gene but this strongly says that
this ferret at least is likely to have WS -- though with all of the
breeding for neural crest markings the individual could even have WS
AND KIT.).
So, it is also important to remember that similar markings when they
have neural crest genetic variations do have the potential to have
different genetic origins.
To understand this it is important to remember WHEN in development
neural crest genetic variation act. The neural crest is one of the
very early portions of the embryo that exist before there are even
organs. They are after the point when the embryo is just a hollow
"soccer ball" of stem cells, though, because the crests are the very
beginning of differentiation. The neural crest is derived from the
cardiac-neural crest when some of those cells become specific for the
things that the cardiac crest makes and others become specific for
what the neural crest makes. Now, what does the neural crest make
though the body? Well, it makes some things you would expect. It
makes the various types of neural systems the body has. See:
http://www.scienceclarified.com/Mu-Oi/Nervous-System.html
for more on the types and what they do. (In fact, the last time I
read up on it as i recall it was thought that the increase in
cardiomyopathy seen in multiple species when there are at least some
forms of neural crest variations is due to damage to the sympathetic
nervous system.) It also creates some jaw structures, some ear
structures, some pigment cells, and more. So, we are talking about
genetic variations which affect one of the earliest groupings of
cells, meaning that the expression of the variation can vary not only
by mutation type but across individuals. Some may be only slightly
affected themselves but their offspring or grandchildren could be so
affected that severe problems will be present. As already mentioned,
there can be multiple ways to affect that cellular grouping, and those
variation don't even exist at just one locus (genetic location) so a
ferret can wind up with multiple neural crest variations all in one
individual which increases the chances for health problems.
IMPORTANT point: for most things noticed from pelage discussed in
relation to genetics what matters is how the ferret appeared when
young. An exception (which is a very different type of genetics) will
be early and permanent extreme lightening and whatever might
genetically incline some to that, but that's a very different genetic
thing than above.
Sukie (not a vet)
Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/
http://www.ferrethealth.msu.edu/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html
all ferret topics:
http://listserv.ferretmailinglist.org/archives/ferret-search.html
"All hail the procrastinators for they shall rule the world tomorrow."
(2010, Steve Crandall)
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