الفهرس 
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Abstract
Vitiligo is an acquired, relatively common, pigmentary disorder of the skin manifested by well circumscribed depigmented white patches. It is frequently associated with a positive family history and affects approximately1–2% of the world population.
It usually begins in childhood or young adulthood but any age may be affected and both sexes are equally affected, however women are more affected than men because of their greater medical attention for cosmetic problems.The etiology of the disease is still unknown. Traditionally, there have been three hypotheses to explain vitiligo: neural, immune and self-destruct hypothesis.
Free radicals are atoms or molecules that contain one or more unpaired electrons in the outer orbit. This makes many free radicals highly reactive, i.e. they have a strong tendency to form pairs to counteract the labile unpaired condition.
To this end, the free radicals gain electrons from any available donor or donate an electron to a suitable acceptor, which in turn become modified into a secondary free radical. This chain reaction can cause biological damage.
Antioxidants transform free electrons into a nonreactive form. Antioxidants regulate oxidative reactions by inhibiting or delaying the oxidation of the substances.
Oxidative stress represents an imbalance between the production and manifestation of reactive oxygen species and a biological system’s ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal redox state can cause toxic effectsthrough the production of peroxides and free radicals that damage all components of the cell, including proteins, lipids, and DNA.
Oxidative stress could be an important phenomenon leading to melanocyte death in vitiligo. Damage caused by free radicals could be a possible pathogenic factor for vitiligo.
The oxidative destruction ofPUFA of phospholipids known as lipid peroxidation, can be in fact considered as a hallmark of the oxidative stress.
Lipid peroxidation is a free-radical-mediated chain of reactions that, once initiated, results in an oxidative deterioration of polyunsaturated lipids. The most common targets are components of biological membranes. When propagated in biological membranes, these reactions can be initiated or enhanced by a number of toxic products, including aldehydes.
MDA is an end-product of lipid peroxidation induced by ROS. It is well correlated with the degree of lipid peroxidation and is an indicator of oxidative stress in vitiligo.
SOD is one of the most effective enzymatic antioxidants and it catalyzes the conversion of superoxide anions to dioxygen and hydrogen peroxide. SOD exists in several isoforms, which differ in the nature of active metal center, amino acid composition, co-factors and other features. There are three forms of SOD present in humans: cytosolic Cu, Zn-SOD, mitochondrial Mn-SOD, and extra cellular-SOD. It protects cells from the toxic effect of superoxide radicals.
There is an important correlation between MDA and SOD in which Superoxide and hydroxyl radicals are the most important radicals in lipid peroxidation so decreased SOD activity could be responsible for the increase of superoxide radicals, which may explain the increased level of MDA in the serum of vitiligo patients.Alsothere is impairment in the antioxidant system in vitiligo, leading to free radical-mediated damage to melanocytes.
This study was aiming toinvestigate the pattern of oxidative stress markers in vitiligo patients and their correlation to the severity of the disease using the VETF score.
The present study is a case control study. It was conducted in the dermatology department of Suez Canal university hospital. The target populations in the present study were 44 individuals, divided into two groups, group 1: patients attending the dermatology clinic suffering from vitiligo and group 2: healthy subjects who were matched with vitiligo patients for age and sex.
Full history of the disease, other skin diseases and systemic disorders weretaken;dermatological examination was done to exclude other skin diseases and confirm the diagnosis of vitiligo and identify its type.
To evaluate the rule of oxidative stress markers in the pathogenesis of vitiligo MDA and SOD serum levels were measured in those patients and compared to those of controls.
The severity of the disease was assessed using the VETF which is a proposal system that combines analysis of extent of area affected, stage of pigmentary loss of disease (staging), and disease progression (spreading).
By analyzing and processing the data obtained from the history, clinical examination and lab work the study declared that:
The studysupported the female predominance which can be due to their more curiosity in cosmetics and frequent dermatologic consultations.
The study declared also that there was a significant higher MDA serum level in the vitiligo patients’ group (5.76 + 2.16) with range (2.6-12.27) compared to the control group (4.52 + 1.28) and range (2.6-7.5) (P˂ 0.05).
According to the study there was a decrease in the level of SOD in vitiligo patients than control group; such decrease may be due to its utilization in detoxication of released ROS.
There is a negative correlation between the MDA and the SOD serum levels in vitiligo group as superoxide and hydroxyl radicals are the most important radicals in lipid peroxidation so decreased SOD activity could be responsible for the increase of superoxide radicals, which may explain the increased level of MDA.
The study showed that there is significant inverse correlation between the SOD serum level and both the extent of area affected and the staging of pigmentary loss of the disease in vitiligo group which means that SOD is protective.
There is significant inverse correlation between the types of vitiligo and the SOD serum level, it is higher in focal than acrofacial than generalized type.
from the above data we concluded that:
1- Oxidative stress may play a role in the pathogenesis of vitiligo and causes the melanocyte damage in vitiligo and that the oxidant/antioxidant system may be affected in all types of vitiligo.
2- Lipid peroxidationplays an important role in the depigmentation of vitiligo.
3- MDA is an indicator of oxidative stress.
4- Superoxide and hydroxyl radicals are the most important radicals in lipid peroxidation. Decreased SOD activity could be responsible for the increase of superoxide radicals, which may explain the increased level of MDA.
5- There is a significant inverse correlation between the SOD serum level and both the extent of area affected and the staging of pigmentary loss of the disease in vitiligo group, Also between SOD serum level and the different clinical varieties of vitiligo as it is higher in focal than generalized type so SOD is protective.