From:
Brett Middleton
Date: 2001-04-19 16:41:00 UTC
Subject: Re: New girl in town (Albinism)
"Bruce Williams, DVM" <williams@e...> wrote:
> However, albinism is a congenital defect in itself, due to the
> defective migration of pigment, which never makes it to the hair
> follicles or the iris. This is the normal albino state.
I've got to disagree with this. Defects affecting embryonic
development can certainly produce a lack of coat pigmentation to a
greater or lesser extent -- blazes, pandas, marked white, and
(possibly) dark-eyed white are created this way. These defects are
also related to deafness and other neural-tube defects, as you state.
However, the term "albinism" is most commonly used for hypopigmentation
resulting from a different mechanism: the albino allele produces a
defective form of tyrosinase, thwarting the biochemical pathway that
produces melanin from tyrosine.
This still qualifies as a congenital defect, of course, and is
associated with vision problems resulting from abnormal retinal and
optic-nerve development. However, albinism doesn't seem to have a very
significant impact on the health and well-being of domestic ferrets,
and there doesn't seem to be any need to discriminate against the trait
in breeding programs, unlike those markings associated with deafness.
In the wild there is considerable natural selection pressure against
albinos, since they are more visible to predators. In domestication
passing hawks are not a big worry, and albinos may even be preferred,
since they are more visible to their handlers in the field when used
for hunting. The vision problems don't seem to be very important in
this species, since ferret eyesight is pretty crummy anyway.
Brett
*SLMW 1.0* First listen to sermon, THEN eat missionary.