Albinism: what is being albino?

Oculocutaneous albinism is a group of hereditary diseases characterized by a depigmentation of the skin, hair and eyes. Indeed, the presence of melanin pigment in the iris and the retina means that albinism is always accompanied by ophthalmological damage.

Albinism, what is it?

Oculocutaneous albinism is due to a defect in the production of melanin pigment by the melanocytes, because of a genetic mutation.

The different types of albinism :

Type 1 albinism

They result from mutations in the tyrosinase enzyme gene which plays a fundamental role in the production of pigment by the melanocytes

Type 1A albinism

There is a total abolition of the tyrosinase enzyme activity. Patients have no pigment in their skin, hair and eyes from birth, making them white-haired with red eyes (the lack of pigment in the iris means that the retina can be seen through).

Type 1B albinism

The decrease in tyrosinase activity is more or less marked. Patients have no pigment in the skin and eyes at birth, making them white with red eyes, but from the first months of life, signs of pigment production of varying intensity appear on the skin and iris (varying from blue to yellow-orange). This is called “yellow mutant” albinism.

Type 2 albinism

This is the most common type of albinism, especially in Africa. The gene responsible is the P gene on chromosome 15 which plays a role in tyrosine transport.

At birth, black children have white skin but blond hair. As they grow up, their hair becomes straw-colored and their skin may acquire freckles, brown spots or even moles. The irises are blue or yellow to light brown.

Type 3 albinism

It is very rare and present only on black skin. It is linked to mutations in the gene coding for TRP-I: the skin is white, the irises are light green-brown and the hair is red.

Other rare forms of albinism

Hermansky-Pudlak syndrome

By mutation of a gene on chromosome 10 coding a lysosome protein. This syndrome associates albinism with coagulation disorders, pulmonary fibrosis, granulomatous colitis, renal insufficiency and cardiomyopathy.

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Chediak-Higashi syndrome

By mutation of a gene on chromosome 1 encoding a protein involved in pigment transport. This syndrome associates an often moderate depigmentation, hair with a metallic grey “silver” sheen, and a very high risk of lymphoma from adolescence.

Griscelli-Pruniéras syndrome

By mutation of a gene on chromosome 15 encoding a protein playing a role in the expulsion of the pigment, it associates moderate skin depigmentation, silver hair and frequent skin, ENT and respiratory infections as well as a risk of blood disease. deadly.

Causes of albinism

Albinism is an inherited disease caused by mutation of a gene encoding the production or delivery of pigment to the skin by melanocytes. The skin and integuments therefore do not have the possibility of pigmenting properly.

The mode of transmission of this mutation from parent to child is in the majority of cases autosomal recessive, i.e. both parents must be carriers of a gene that is not expressed in them and that these two genes (one paternal, the other maternal) are found in the child.

We all carry two genes, one of which is dominant (which expresses itself) and the other recessive (which does not express itself). If the recessive gene has a mutation, it is therefore not expressed in the person with a dominant gene that is not mutated. On the other hand, during the formation of gametes (spermatozoa in men and ova in women), half of the gametes inherit the mutated gene. If two people conceive a child and are carriers of the mutated recessive gene, then there is a risk that the child will have originated from a sperm carrying the mutated recessive gene and from an egg carrying the same recessive gene. As the child does not have a dominant gene but two mutated recessive genes, he then expresses the disease. This probability being quite low, it does not.

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Who is most affected?

Albinism can affect Caucasian populations but is more common in Africa on black skin.

Evolution and possible complications

The main problems caused by albinism are ocular and cutaneous. There are other blood or organ problems only in the very rare syndromes of Hermansky-Pudlak, Chediak-Higashi and Griscelli-Pruniéras.

The skin risk

White light is made up of several “assembled” colors, which “separate” for example during the formation of a rainbow. A color results from the property that the molecules have to absorb all the colors of the light except one, for example the blue absorbs all except the blue, which is reflected on our retina. Black results from the absorption of all colors. The black pigment of the skin allows to absorb the colors of the light but also and especially the Ultra Violet rays (UV) which cause a carcinogenic risk for the skin. The lack of pigment resulting from the disease makes the skin of patients “transparent” to UV rays because nothing absorbs them and they can penetrate the skin and create damage to the cells, causing a risk of skin cancer.

Children suffering from albinism must therefore avoid any contact of their skin with UV rays by planning their activities (sports in the gym rather than outdoors for example), wearing protective clothing and sun products.

Ocular risk

Patients with albinism are not blind, but their visual acuity, both near and far, is diminished, sometimes severely, requiring the wearing of corrective lenses, most often tinted, to protect the eyes from the sun because they too are pigment-free.

From kindergarten onwards, the albino child suffering from visual deficiency is placed as close as possible to the blackboard and, if possible, is assisted by a specialized educator.

The symptoms of albinism

On the skin

In the most severe forms, the diagnosis is usually obvious from birth: the skin is pinkish white, the hair and body hair are snow white or even blond.

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In less severe forms, the hair is blond and darkens after a few months, becoming progressively light brown in adolescence.

We have seen that the most frequent forms, in particular “Tyrosinase positive”, could see freckles, brown spots and moles appear during childhood.

The skin is very sensitive to UV rays: in the absence of sun protection, skin cancers appear.

At eye level

In the most severe forms, the irises are bluish gray, translucent, therefore appearing red (we see the retina through). Babies can’t stand light and often have squint. Visual acuity is severely impaired.

In less severe forms, the irises are blue, yellow-orange or even light brown. Visual acuity is less impaired.

Risk factors

Albinism is a genetic disease. The only risk factor is therefore heridity. Mutations are more frequent in Africa.

 Our doctor’s opinion

It is important to keep in mind that patients with albinism, even if they are often visually impaired, have a perfectly normal physical and intellectual development. It is therefore very important to inform the teaching team as early as kindergarten so that the child can follow a normal schooling.

Moreover, we sometimes encounter a bad understanding or a bad compliance of the entourage during the occurrence of albinism on black skin, because the close family (parents, siblings…), the cousins with whom the child plays never had the habit of protecting themselves from the sun, we must ask them to play indoors with the affected child…

Treatments and care for albinism

There is currently no effective gene therapy for abinism. The only treatment is sun prevention to avoid carcinogenic risks: seek shade and protect the skin and eyes from the sun by the use of covering clothes, hats, glasses and high factor sun creams on exposed areas.

Regular monitoring by a dermatologist and an ophthalmologist is desirable throughout life.