الفهرس Only 14 pages are availabe for public view
 |  | from | 132 |  |  |
| | | from | 132 | | |
Abstract
Vitiligo is a non contagious idiopathic or acquired pigmentation disorder characterized by sharply-defined milky white patches of variable shapes and dimensions affecting skin, overlying hair& mucosae. This can cause great distress and concern particularly for those whose natural colour is dark . Vitiligo is a common skin disorder affecting approximately 0.5% - 2% of the population worldwide, irrespective of race or ethnic origin. Etiology is still unknown, but some evidence-based pathogenetic hypotheses have been proposed to explain the loss of melanocytes in epidermis such as the autoimmune, autocytotoxic and neural hypothesis. Over the last years a bipolar approach has characterized the studies on the pathogenesis of vitiligo. A pole corresponds to the idea of an immune-mediated damage of the melanocytes whereas the other pole refers to a toxic-mediated impairment of the cells . - Reactive oxygen species (ROS) such as O , H O , OH are 2 2 essential for life, because they are involved in cell signaling, melanogenesis and are used by phagocytes for their bacteriocidal action. Nonessential production of ROS, i.e., oxidative stress, can also be induced by environmental factors such as UV radiation, toxins, stress etc. Prime targets of ROS are the polyunsaturated fatty acids (PUFA) in the membrane lipids. This attack causes lipid peroxidation and further decomposition of peroxidized lipids yields a wide variety of end- products, including malondialdehyde (MDA). These products can cause DNA damage and lead to cytotoxicity, mutagenicity, cell death and could be a possible pathogenic factor for vitiligo.