Albinism
The true Albino gene is cc or amelanistic and removes all color from the skin, fur and eyes leaving an
animal with pink skinned, white hair, and red eyes because the animal lacks melanin. Partial Albinisms are at the same location as the Albino gene
but do not completely remove the color. The genes responsible for Siamese and Burmese cats are dependent on temperature; the cooler parts of the
animal are darker. These are the 5 points: nose, ears, paws, tail and genitals. With decreased temperatures the contrast between point color and
body color will increase. Some partial albinism genes cause the eyes to be blue instead of pink or red. This is seen in dogs with the merle gene.
Anerythristic albinos lack red color and will show some color and patterning. Some animals will be bluish-gray. Axanthic albinos lack the
yellow color also showing color and patterning. Tyrosinase-negative albinos lack tyrosinase - the enzyme which synthesizes melanin. This usually
causes the animal to be pale yellow or cream with pink eyes. Tyrosinase Positive albinos can produce melanin but not tyrosinase. These animals
often are fawn, platinum, or lavender in color.
Leucism is similar to albinism but is a different gene. The animals have darks eyes and some pigmentation including phantom markings. This is
seen a lot in reptiles.
There are issues with the lack of melanin during fetal development. Melanin is used to help shield the body from UV rays. However some must get
through in order for the body to produce vitamin D and absorb calcium and phosphorus in the intestines. Too much UV and one of the vitamin B's
(folic acid) is broken down and one of the results is anemia. Without melanin the intestines don't develop properly. Horses with a certain gene
when bred together produce Lethal White Syndrome (LWS) foals that die after nursing only once. Their intestines are not developed enough to handle
digesting anything even with surgery. Some have intestines so underdeveloped they have no external opening for feces to exit.
These are examples of combining a color with a partial albinism. Above 
is a calico siamese cat. Her ears, nose, paws, and tail are full color while her body color is diluted. Below 
are supposedly brother calicos. The one on the left 
is solid colored but the one on the right 
is also siamese. You can see the difference in the color on the faces. In most species
(including cats) male calicos are rare and usually sterile. Guinea Pigs are one exception I know of.
References
This page was last edited on
October 12, 2011
