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Hypopigmentation of the skin: Dermatologist and Albinism
Doctor Monica Pau
The skin colour of an individual is determined mainly by the presence of the melanin pigment, although other factors can help such as the relative amount of oxidized and reduced hemoglobin and the presence of other pigments such as the carotenoids.
Melanin is produced by the melanocytes inside particles called melanosomes.
The biochemical process that leads to the production of melanin starts from the tyrosine under the direction of the enzyme tyrosinase, which leads it through several intermediate processes and finally to the formation of eumelanin, pheomelanin and tricochromes.
Pigmentation disorders can be distinguished by either excess or hyperpigmentation (congenital or acquired, localized or diffused) or lack or hypopigmentation (congenital or acquired, localized or diffused).
Ocular-cutaneous albinisms are classified within the category of diffused congenital hypopigmentation and are mainly due to the absence or the deficiency of the enzyme tyrosinase and consequently the lack of melanin production.
Whatever the phenotype and the clinical diagnosis of the disease is, all albinos have a particular sensitivity to the light.
In particular, the greatest stimulus for skin pigmentation is due to ultraviolet radiation or UV, which fall in the spectrum of electromagnetic radiations, x-rays and visible light. There are three types of ultraviolet radiation: UVC, UVB, and UVA, depending on wavelengths ranging from 200 to 400 nm.
The intensity and the spectrum of the UV rays that reach the earth's surface depend on many environmental factors (altitude, longitude, time of the day and of course weather and climatic factors).
When UVA or UVB rays hit the skin they produce erythema and carcinogenic effects causing photo-aging and mutagens effects. They both stimulate the production of melanin, which counteracts the effects caused by UVA and UVB radiation. To avoid harm caused by intense sensitivity to UV rays albinos should protect their skin by wearing appropriate protection, ex. High SPF sunscreen, sunglasses, large hats, long shirts and pants, etc.
Sunscreens act in a chemical and physical way first by absorbing UV radiation and secondly by diffusing the light, they can also take action against the UVB and the UVA or each other's. Suncreens are classified according to the sun protection factor (SPF) and protection index that indicates the amount of radiant energy that a filter can absorb before erythema occurs. Therefore, suncreens must be chosen according to skin type, that is the individual sensitivity to UV light and keeping in mind the place of exposure.
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