Introduction: Albinism, also known as albinism, is a disease caused by the lack or insufficiency of melanin synthesis, which causes the patient to lose pigment (color) in part or all of the skin, eyes or hair. The patient has white skin, Barbie hair, red eyes, albinism patients can not accept the stimulation of strong light, due to the fear of light, albino children gradually receive social attention and are called "moon" children.
First, the pathogenic mechanism/characteristics
(1) Genetic characteristics
Albinism is a hereditary leukoplakia that causes deficiency and synthesis disorders in the skin and some accessory organs due to genetic defects, lack of tyrosinase and decreased function. As a result, the patient lacks pigment in the retina, and the iris and pupils appear pale pink, so there are red eyes. Albinism is a familial genetic disorder.
According to data from the National Organization for Albinism and Pigment Degradation (NOAH), about one in 17,000 Americans has a case of albinism, while in East Africa (about one in 3,000 Americans) the incidence is higher. Why is there such a difference? Mutations in the OCA2 gene are the main cause of albinism in Africans, which may be the most primitive gene mutation in Africans, which has been preserved in the reproduction of Africans, and for some reason the mutated gene has been preserved, resulting in a higher incidence in East Africa.
(2) The reduction of melanin leads to the whitening of the skin
There is a class of cells in the human body, called melanocytes, that are responsible for producing the pigments needed for the skin, hair, and eyes. It is precisely because the genetically mutated melanocytes in patients with albinism interfere with pigment production in the body or inhibit the distribution of keratinocytes. Keratinocytes are the main cells that synthesize the outer layer of the epidermis or skin. Among the five gene mutations that cause albinism, ocular cutaneous albinism type 1 and ocular cutaneous albinism type 2 are the most common. That is, eye dermatosis can affect the eyes and skin.
(3) Caused by genetic mutations
The TYR gene is mutated in patients with ocular cutaneous albinism type 1 (OCA1), and the TYR gene of OCA1 is a gene that synthesizes tyrosinase, which delivers the amino acid tyrosine to pigment molecules in the skin, hair, and eyes. Ocular cutaneous albinism type 2 (OCA2), most common in African albinism, is caused by a mutation in the OCA2 gene and codes for the P protein. But the function of the P protein is unclear.
2. Clinical symptoms
(1) Lack of pigment in the body
People with OCA1 have snow-white skin and hair and no pigmentation in their eyes. The part of the iris around the pupil (the colored part around the pupil) is slightly bluish, while the pupil may appear full red. Red may be the light that enters the pupil and is reflected through the retinal blood vessels, while the photosensitive layer is located behind the eyeball. Normally, as pigment molecules in the retina absorb sunlight, the pupil appears black, which prevents it from returning to the outside world.
Patients with OCA2 can produce small amounts of pigment molecules that can turn hair blond or brown. Their iris may be blue-grey or pale grey, and the pupils are dark red.
(2) Decreased vision
People with albinism are usually blind because photoreceptors (the retina inside cells that sense light) receive oversaturated light and then transmit confusing information to the brain. When you see an albino patient, you will find that they have an eye shock or eyeache at the same time. The eye's response to complex visual stimuli.
(3) Other symptoms
Keratinocytes of the skin of melanoma, if the skin pigment is insufficient, can cause allergic reactions. Usually, melanocytes give keratinized cytochromes, which act like umbrellas, preventing nucleic acids containing DNA from being exposed to the sun's ultraviolet rays. Patients with cutaneous albinism are at high risk for squamous cell carcinoma, a type of basal cell carcinoma that can invade deep tissues. They can also experience immature cells with premature aging. In addition, melanin can prevent ultraviolet radiation, prevent the production of wrinkles and the degeneration of elastic tissues.
Third, albinism can be divided into two major groups
One is the more common ocular cutaneous albinism, which is caused by the body's inability to produce the melanin the body needs. The other is albinism that accompanies abnormalities of the immune system, in which the patient is caused by a lack or insufficiency of melanin and other defects in cellular proteins.
There are three main categories of albinism
1. Ocular albinism (OA)
Patients who only have a decrease or lack of pigmentation in the eyes will have symptoms of decreased vision and fear of light.
2. Ocular skin albinism (OCA)
In addition to the lack of eye pigmentation and symptoms such as decreased vision and light, the patient's skin and hair are obviously underpigmented.
3. Albinism syndrome
In addition to symptoms of ocular skin albinism, patients have a number of other abnormal symptoms, such as Chediak-Highashi syndrome with decreased immune function and Bleeding diathesis Hermansky-Pudlak syndrome, both of which are albinism, but both are rare.
5. Treatment methods
Some researchers at the University of Minnesota in the United States have tried to develop a gene therapy method in an attempt to cure albinism by correcting mutated genes. Now, the researchers have successfully cured mice with albinism, but it will take some time to apply genetic repair to humans. Therefore, there is still a lack of a complete treatment for albinism. To prevent, only patients with albinism can be advised to prevent sun exposure.
In addition to humans, will animals get albinism?
Albinism is a genetic disease that is common in nature, and many animals, including humans, may have albinism. However, animals with albinism are still rare in nature, and it is extremely difficult for such animals to survive in nature, because animals with albinism will have difficulty in foraging, so it is difficult for the animal to survive in a predatory environment. Mammals, reptiles, amphibians, and low vertebrates can also suffer from albinism, but these organisms have pigment-producing cells in addition to melanocytes, so they are not completely colorless. There are albinos of alligators in the Cincinna Zoo.
Seventh, love the children of the "moon" and eliminate discrimination, starting with you and me
The troubles in the lives of people with albinism are not only physical, but more psychological. They often have inferiority complexes because their appearance is different from ordinary people, and they are reluctant to associate with others. Unfortunately, normal people also have different degrees of discrimination against albinism patients, which should not be.
Conclusion: For people with albinism, in addition to paying attention to avoiding sun exposure and long-term eye protection, the most important thing is to prevent social discrimination against them. The purpose of popularizing the genetic knowledge of albinism is to call on all sectors of society to eliminate discrimination against albinism patients and give children more humanistic care.