Tigers of any color are top-end predators, but white tigers are rare outside of zoos. A white tiger is a variation of a Bengal tiger, according to Southwick's Zoo. The white fur is associated with a weakened immune system and other genetic problems.
White tigers are not albino. A white tiger's unusual color is caused by a recessive gene that suppresses expression of the pigment pheomelanin; and, that pigment is normally responsible for red and yellow coloring. Some white tigers also carry a gene that makes their stripes very pale.
White tigers share an enzyme with Siamese cats and Himalayan rabbits that causes their fur to darken in response to cold. White tigers bred in captivity often have crossed eyes, crooked backbones, kidney problems and reduced fertility as the result of inbreeding.