From:
Sukie Crandall
Date: 2001-04-25 15:31:00 UTC
Subject: Re: Albinism, Depigmentation, and Domestication
Bob wrote:
>Those animals (almost exclusively domesticated, but
>including humans) having blazes, stripes, piebald coloration, or white
>foreheads and bibs are developmentally depigmented. Most depigmentation
>occurs because of a metabolic disruption of normal pigmentation, and is
>an evolved trait which produces seasonal coat coloration changes. This
>is typically tied to photoperiod cycles and is regulated by hormones.
>But in domesticated animals, something else is happening; depigmentation
>occurs because the cells which produce pigments are prevented from
>reaching their final destinations, leaving specific areas void of
>pigmented cells. See the difference?
And don't forget that life-long (not developed from aging and not
disappearing over seasons) panda-heads and blazes are consistent with
the widely distributed (throughout Mammalia and perhaps before)
neural crest disorder, Waardensburg Syndrome. WS is a genetic
disorder which normally is quite rare, with three so far discovered
alleles that can lead to it (and multiples of those can happen in
conjunction with each other). Expression is variable, with deafness
being possible and intestinal problems (I don't know details and
really should read up on it more if i get some time.) have been seen
in other species in some with the syndrome.
The proportion of WS ferrets has increased markedly through the
years. Heck, 15 to 19 years ago even silver-mitted ferrets were rare
and WS ferrets burst on the scene after them and then became the new
"hot" fancy to have and to talk-up. When we first began to have
ferrets (19 years ago) there pretty much were albinos, sables, and a
lighter patterned one that back then was called "siamese". Some few
places had a few fancies of assorted types and got top dollar for
them even with no one knowing if they might be less healthy. (Then
some began breeding more and more fancies of many types...
Fortunately, now some breeders are keeping more thorough line and
health records, and some shows are being more careful about foci on
differences in appearances which have unknown health or longevity.)