do you think there is a human race with white eyes?
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Albinism is a
congenital disorder characterized in humans by the complete or partial absence of
pigment in the skin, hair and eyes. Albinism is associated with a number of vision defects, such as
photophobia,
nystagmus, and
amblyopia. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers. In rare cases such as
Chédiak–Higashi syndrome, albinism may be associated with deficiencies in the transportation of melanin granules. This also affects essential granules present in immune cells leading to increased susceptibility to infection.
[3]
Albinism results from inheritance of
recessive gene alleles and is known to affect all
vertebrates, including
humans. It is due to absence or defect of
tyrosinase, a copper-containing enzyme involved in the production of
melanin. It is the opposite of
melanism. Unlike humans, other animals have multiple
pigments and for these,
albinism is considered to be a hereditary condition characterised by the absence of melanin in particular, in the eyes, skin, hair, scales, feathers or cuticle.
[4] While an organism with complete absence of melanin is called an albino, an organism with only a diminished amount of melanin is described as
leucistic or albinoid.
[5] The term is from the
Latin albus, "white".
here are two principal types of albinism:
oculocutaneous, affecting the eyes, skin and hair, and
ocular affecting the eyes only.
There are different types of oculocutaneous albinism depending on which gene has undergone mutation. With some there is no pigment at all. The other end of the spectrum of albinism is "a form of albinism called rufous oculocutaneous albinism, which usually affects dark-skinned people".
[6]
According to the
National Organization for Albinism and Hypopigmentation, "With ocular albinism, the color of the iris of the eye may vary from blue to green or even brown, and sometimes darkens with age. However, when an optometrist or ophthalmologist examines the eye by shining a light from the side of the eye, the light shines back through the iris since very little pigment is present."
[7]
Because individuals with albinism have skin that entirely lacks the dark pigment melanin, which helps protect the skin from the sun's
ultraviolet radiation, their skin can
burn more easily from overexposure.
[8]
The human eye normally produces enough pigment to color the
iris blue, green or brown and lend opacity to the eye. In photographs, those with albinism are more likely to demonstrate "red eye", due to the red of the
retina being visible through the iris. Lack of pigment in the eyes also results in problems with vision, both related and unrelated to
photosensitivity.
Those with albinism are generally as healthy as the rest of the population (but see related disorders below), with growth and development occurring as normal, and albinism by itself does not cause mortality,
[9] although the lack of pigment blocking
ultraviolet radiation increases the risk of melanomas (skin cancers) and other problems.