Well I'm no expert on genetics of color, but I have a suggestion.  Check out
the literature on breeding canaries for color.  Also check out mice breeding
for color and coat characteristics.  Jackson labs would be a good source of
information on this.  My recollection on canary coloring is that yellows
come from a mutation in the melanin gene that leaves intact the other color
genes such as eumelanin and one other that I can't remember.  I used to own
a corn snake with a coloring that made me think that it was mutant in its
melanin gene because it was orange rather than brick red.  Albinos in mice
and cats traditionally have various neurological problems that stem from
improper growth of certain sensory nerve tracts for example siamese cats
(which are I believe a temperature sensitive form of albinism) have
incomplete crossing over of their visual system that makes them appear
cross-eyed.  Steel mice (a black eyed white mouse) also have some visual
system anomilies.
 
Max
[Posted in FML issue 1908]