The DNA contained in each of your body’s cells contains all the information necessary for the development and functioning of an organism. Therefore, any defect that is located in the genetic material can degenerate into a malfunction and health problems.
A clear example is albinism : this genetic condition is characterized by the total or partial absence of pigmentation (melanin) in the skin, hair and iris of the eye.
The albino condition is not exclusive to humans, it also occurs in animals (a memorable example was Snowflake, the albino gorilla at Barcelona Zoo) and plants. In the latter case, they have an absence of other classes of pigments, such as carotenes, since they do not naturally present melanin.
However, lack of pigmentation is not the only characteristic of this alteration. Albino people, in fact, have many associated problems , both biological and social.
The function of pigments
Pigmentation in humans is carried out by cells known as melanocytes , which make the two classes of melanin inside them from the amino acid tyrosine: eumelanin (dark) and pheomelanin (light).
The combination in different proportions of these two originates the fan of colors of eyes, hair and skin. Its main function is to protect the rest of the cells from ultraviolet light, which is harmful to the DNA.
Genetic causes of albinism
Albinism has an important genetic component that presents an autosomal recessive inheritance. It is simple to understand: our genetic material is made up of 23 pairs of chromosomes, one half coming from the mother and the other from the father (each pair has two homologous genes in the same position, one per pair, known as an allele). Normally, only one of the two genes of an allele needs to be working well for it to function properly. Well, in this case we speak of autosomal recessive because the two genes of that allele are wrong.
For this reason it is explained how non albino parents can have a child with this condition, since the parents are carriers , each one has a wrong gene.
There are different types of albinism
Not all albino people have the same genetics, but there are different classes that depend on the gene that is affected. The truth is that not all of them lead to the loss of skin and hair pigmentation, only share the decrease in visual acuity due to various alterations in the eye.
Classically, two major groups have been defined : ocular-cutaneous albinism (OCA) and ocular (OA) . As its name suggests, the former affects melanin in the eye as well as in the skin and hair, unlike the latter, in which only melanin present in the iris is affected. The lack of pigmentation may also be associated with other serious organic disorders, such as in Hermansky-Pudlak syndrome.
Currently up to 18 genes are known to be involved, with 800 possible mutations . To give an example, one of the most common types in the West is OCA1, as well as being the most severe, in which the affected gene is the one that synthesises the enzyme tyrosinase (TYR). This protein is responsible for transforming the amino acid tyrosine into melanin within the melanocytes. Of course, if the enzyme does not work, no melanin is synthesized in the body.
People with albinism who have a total or partial lack of melanin in their skin and hair have problems tolerating solar radiation . They are easily reddened and the probability of suffering from skin cancer increases, so they need to protect themselves from the sun, either by clothing or by appropriate cream.
The lack of pigmentation in the eye, a common characteristic of all its types, produces photophobia, that is, it does not support direct light well . It is common to wear sunglasses to protect your eyes from the light. It should be added that albino people also present different visual anomalies that make their acuity difficult, so one of their biggest problems is in their vision.
Albinos in the world
The global frequency of albinism is low, 1 in 17,000 people. But there are different types, each with its prevalence, and their degree of dispersion also depends on where in the world they are spoken of. For example, in Japan there is a high prevalence of the OCA4 type, due to some inbreeding; and on the island of Puerto Rico, which is considered the country with the highest incidence of this genetic condition, there are many more people affected in its most dangerous aspect, that of Hermansky-Pudlak syndrome.
Africa is another example. The continent where albinos are most frequently found, moreover, does not make things easy for albino people: due to archaic beliefs, some cultures kill these people and chop them into pieces with the aim of selling them to shamans for their spells . In the case of women it is even worse, since it is thought that they have the capacity to eradicate HIV through the sexual act, so they rape them and are infected with the disease. Adding this to the fact that Africa is the region of the world with the most solar radiation, the quality of life of albino people is abysmal.