In A Nutshell
The different types of albinism all have to do with the body’s inability to produce melanin, leading to white, gray, or cream-colored hair and skin (but not necessarily red eyes). Leucism occurs when color pigments are produced in a lower amount than normal, and normal skin, fur, or feather patterns and textures remain. Isabellinism happens when normally dark-pigmented areas develop as a sort of washed-out grayish-yellow, and it’s supposedly named for an archduchess who refused to remove her underwear for three years.
The Whole Bushel
Every so often, a lucky nature photographer snaps a photo of a rare white animal. And every so often, one is born in captivity.
White alligators, white giraffes, white grizzly bears—they often don’t survive long in the wild without the benefit of their natural coloring, but they never fail to capture the world’s collective heart.
The standard description of a white animal is usually to call it an albino, but there are a few different genetic conditions that can result in this stunning coloration.
Humans with albinism are said to be clearly recognized by their red or pink eyes, but that’s not actually a defining feature of the condition. People can be diagnosed with albinism regardless of eye color, as the official defining factor is related to the production of melanin, the pigment that gives hair, skin, and eyes their color.
It’s estimated that about one in every 18,000–20,000 people in the United States have some form of albinism.
There are several different forms. Oculocutaneous albinism (OCA) happens when there’s a mutation in one gene. OCA results in white skin, white hair, and blue eyes.
X-linked ocular albinism occurs only in men, and manifests as light-colored skin and hair that’s still considered within the “normal” range.
Hermansky-Pudlak syndrome has symptoms similar to OCA, but it’s more common in Puerto Rico and it’s usually accompanied by blood, lung, and bowel disorders.
And Chediak-Higashi syndrome is a rare version that gives hair a silver cast and causes skin to be grayish. White blood cell counts are often affected as well, making people with this type more prone to infections.
As for eye color in humans with albinism, the red, pink, or purple appearance can show up when the light is just right. While the eyes themselves can be blue or brown, the lack of pigmentation can make them seem translucent. When the light is just right, it can reflect off the blood vessels in the eyes and make them appear red.
Another condition, called leucism, is a genetic condition in which animals appear paler than normal and, in some cases, even white. While an albino animal will be pure white, one with leucism will still display the stripes, spots, or other kinds of patterning that their more standard brethren show.
Unlike an albino animal, they’ll still produce pigments, just in a smaller amount. Both conditions can appear in the bird world. While most albino birds tend to have a tragically short life span, leucistic birds have a different set of problems. They generally inherit feathers that wear more quickly, and in some cases, they may be condemned to the single life, not sporting the bright plumage that many species depend on for courtship.
Science is still bickering about the difference between leucism and isabellinism. According to the Ornithological Society of New Zealand, the former manifests more as white, while the latter is a uniform grayish-yellow seen most clearly (although rarely) in penguins. While they also report that albino penguins seem to be ostracized by their companions, isabelline penguins have been seen leading perfectly normal lives.
There’s definitely an easy way to remember just what color an isabelline animal is. The name supposedly comes from a legend about the Archduchess Isabella of Austria who, for some unspecified reason, made a bizarre pledge at the start of the 17th century. Until her husband conquered the city of Ostend and united the provinces of their country, she would not remove or wash her underwear.
“Isabella” is the name of a color, a sort of grayish-yellow.
We feel we can safely presume it is also the color of the underwear in question when the unification finally happened after three years of fighting.
Respectable sources call the story of Isabella a nonsense legend, but it’s still useful as a memory device.
Show Me The Proof
Notornis: “A review of isabellinism in penguins”
British Trust for Ornithology: Leucism & albinism
Berkeley Science Review: Why White’s Not So White After All: The Story Of Leucism
Mayo Clinic: Albinism