From:
Sukie Crandall
Date: 2005-10-08 19:40:33 UTC
Subject: [ferrethealth] need some verification
To: sewallen@hotmail.com, ferrethealth@smartgroups.com
Well, I have read about a LOT of things that are linked to neural
crest problems, but not intellectual impairment -- at least not so
far, so personally I would be inclined to use a grain of salt until
references show up.
I have heard from a human genetics counselor that there ARE brain
differences showing up in the studies of some humans with some neural
crest genetic variants, but she did NOT mention any of them being
intellectual ones.
Is it possible that some deaf mother ferrets -- not being able to
hear cries failed to feed some kits enough, or perhaps were too rough
with them or accidently oxygen deprived them for a while? Sure.
Also, sometimes intellectual impairment is present when many
malformations also are. We had one little one like that among the
malformed ones we have taken in; she was incredibly impaired
intellectually and her senses were fine.
My suspicion is that some people just as not as good with animals who
are deaf or partly deaf. One neural crest one we had could only hear
low pitched noises, and I have heard of the opposite. Sometimes it
is harder to process partial auditory information than no auditory
information. There is a wonderful human study on elderly people who
were misdiagnosed as having Alzheimers when actually they were trying
to piece together fragments of sound into a useable whole and it
would cause them to lose the path of the discussion. Remove sound
with such individuals and use a different way of expressing a thought
and there is no impairment. (I wanted to send you directly to that
reference, but that is among the things lost when my failed fan
bearing caused overheating of the hard drive.) Hey, you are in luck.
My marvelous Steve had it in an archive:
<http://www.eurekalert.org/pub_releases/2005-08/bu-hli082905.php>
It really explains a LOT for ferrets who are partly deaf as well as
for humans in that situation.
The best place I know to find links to references about genetics that
can affect ferrets is
http://groups.yahoo.com/group/Ferret-Genetics/
The FHL Archives is good, too.
In each of those if you look at past posts of Dr. Brett Middleton who
is a geneticist you will notice that Waardenburg is NOT the best fit
for what is seen in most ferrets with these markings (though there
may be some with that). The KIT Oncogene is the better fitting
neural crest variant. The most accurate thing is to just say "Neural
Crest Genetic Variation".
The neural crest is a very early fetal area with cells that will
later become a wide range of structures. It is turn is split off
from the cardiac neural crest. These crests precede organs or
features. They are very early. As a result altering them affects
many tissues to degrees which virtually always inconsistently vary
among individuals (variable expression).
A number of the neural crest mutations are extremely ancient but very
consistent throughout the animals affected when a population is
considered. This is probably no surprise when you consider how early
in the fetus these exist. Neural Crest mutations are a very hot area
in human genetic counseling because, of course, when you alter the
innervation of multiple tissues very early on and then throughout
life you runt the risk of seeing a number of changes. Some well
documented or reported alterations which are seen more frequently
(sometimes much more frequently) with neural crest genetic variant
markings include (but are not limited to): deafness, eye defects (not
reported so far in ferrets but suggested and there may be
undiscovered ones in ferrets; after all, it was only recently found
that albino ferrets have peripheral vision field defects), mandible
(lower jaw) malformations that prevent them opening fully, dysphagia
(difficulty swallowing), syndactyly and polydactyly (toes in a
sheath, or extra toes), cardiomyopathy -- especially the harder to
find hypertrophic cardiomyopathy (very well documented in a range of
mammals so start chest imaging earlier on these ferrets), skull
malformations, poor intestinal innervation and resulting medical
problems, and several of the neural crest mutations (including the
KIT Oncogene and LEOPARD Syndrome increase malignancy rates).
Thanks to the NIH recent advances have been made into inquiries of
how many kidney genetic woes might increase in rate with neural crest
variants. One thing slated for study in this regard is the formation
of cystine stones (a problem for which one other major genetic
variation is reasonably documented in mammals and several minor ones
are). So over time there may be more to learn on that score, too.
On a personal note, this intrigues me partly because both of the
ferrets we have with a tendency to form cystine stones on diets with
more than 35% protein both have neural crest markings that are
commonly associated with the KIT Oncogene. Neither has a blaze or
panda head -- the better known neural crest genetic variant markings
which can be seen with several neural crest variants in mammals such
as the KIT Oncogene and Waardenburg, but both have partial mitts and
one has a partial bib.
Ferrets with neural crest genetic variant markings should have more
frequent veterinary examinations and earlier "old age" testing and
should not be bred. Sadly, because of variable expression and
because you can't see white markings under the coats of albinos or
DEWs these conditions may at times be hidden from view.
-- Sukie (not a vet)
Ferret Health List co-moderator:
http://www.smartgroups.com/groups/ferrethealth
FHL Archives fan:
http://ferrethealth.org/archive/
and
http://fhl.sonic-weasel.org
International Ferret Congress advisor:
http://www.ferretcongress.org
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