From:
Sukie Crandall
Date: 2010-04-19 17:52:26 UTC
Subject: [ferrethealth] Re: [Ferret-Genetics] Re: Genetics of silvers
To: fg <Ferret-Genetics@yahoogroups.com>, fhl <ferrethealth@yahoogroups.com>
In Ferret-Genetics on Apr 19, 2010, at 6:05 AM, ACH wrote about how
the genetics of ferret silvers in parts of Europe have caused warning
to circulate among European ferret breeders due to many extreme
serious problems.
Always remember with neural crest genetics that there is what is
called Variable Expression. This means that some individuals may have
few of the characteristics and burdens BUT others in the very same
family line can be hugely handicapped. That has to do with these
mutations causing changes in the very early fetus even before organs
form. So, yes, there can be ones who wind up okay, but they can have
siblings, descendants, or predecessors with major health and longevity
burdens, even behavioral burdens in some with deafness since not
everyone knows how to train deaf ferrets or even that their ferrets
are deaf or partly deaf, and then they can exacerbate difficulties
with poor training choices.
Polka dots that are not bilaterally symmetrical on the head (or any
other coloration that is not reasonably similar one each side of the
head) can be a pelage marking that goes along with defects of the
aortic arch.
Decades ago one of the U.S. breeders came up with a type of ferret
which had patchwork coloration, drop dead gorgeous and the coloration
bred true. Unfortunately, drop dead wound up being the critical
phrase and they all did so when their aortas failed, usually by the
age of 3. All were neutered. I knew one of them and adored him as a
individual, marvelous personality so it still hurts that he was doomed
from the start.
Neural crest genetic situations can have multiple causes which change
the early fetal neural crest. There are multiple genetic variations
and even multiple genetic loci (locations on the chromosomes) which
alter the fetal crest. So it is even possible to saddle a creature
with more than one of these burdens simultaneously.
Some of the very serious problems that can happen at increased rates
or are currently under study with types of neural crest disorders
include but are not limited to:
cardiomyopathy (many species and thought to be due to damage to the
sympathetic nervous system)
kidney damage (due to nerve damage, and currently under further study
in other species)
intestinal motility problems (strongly suggested by some ferret vets
due to nerve damage, and mentioned by a geneticist as existing in
some other species including humans as Hirschsprung's Disease )
deafness
mandibular ramus attachment malformation so difficulty opening jaw
right (from the same fetal cellular region change as deafness)
polydactyly and/or syndactyly (extra toes, or joined toes)
microophthalmia (eyes which never formed right and are very tiny)
which is more often seen with
WS
corneal malformations
increased rates of a host of malignancies (Yes, some of these
predispose individuals to "cancers"
and that is well documented in multiple species.)
Per Dr. Brett Middleton, a genetics professor in a major university,
the most common neural crest markings seen in U.S. ferrets are
probably due to KIT (which does cause a lot of white spotting and is
among the neural crest variations that are considered oncogenetic) but
there may be some with WS or other neural crest disorders. He also
says that even situations in which the mitts and bibs are cleanly and
completely a replacement of black with white may be a neural crest
variation, but one which seems to be milder than most of the others.
Partial mitts, partial bibbs and spotting are more likely to entirely
different neural crest genetic variations -- so there is a real risk
for discussion confusion when people lump these together in
discussions if they don't understand the differences between subsets.
Most neural crest disorders cause increased portions of white fur
areas, but there are some that cause black ones, with the most common
of those dark spot genetic variations being named the initials LEOPARD
which is also oncogenetic (increases malignancy rates), connected to
higher rates of cardiomyopathy, and tied to a host of other problems.
Okay, those were off the top of my head.
I only have a tiny bit of time so people will need to search
themselves but these may help.
DO see past posts of Dr. Brett Middleton in the archives of both the
Ferret Health List and Ferret Genetics:
http://ferrethealth.org/archive/
http://tech.groups.yahoo.com/group/Ferret-Genetics/
General info on neural crest:
http://embryology.med.unsw.edu.au/Notes/ncrest2.htm
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1414065/
http://www.fasebj.org/cgi/content/abstract/8/10/699
In Ferret-Genetics on Apr 19, 2010, at 6:05 AM, ACH wrote about how
the genetics of ferret silvers in parts of Europe have caused warning
to circulate among European ferret breeders due to many extreme
serious problems.
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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