الفهرس 
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Abstract
Vitiligo is a progressive depigmenting disorder characterized by the loss of functional melanocytes from the epidermis affecting 0.5–2% of the population worldwide.
The aetiology of vitiligo is not clear, and although various hypothesis have been proposed. It has been suggested that autoimmunity plays an important role in the pathogenesis of vitiligo. However, the detailed immune pathogenesis of vitiligo remains not completely understood .
Recently, a connection between some autoimmune diseases and vitamin D deficiency has been reported, also vitamin D deficiency was suggested to act as an environmental trigger for the induction of autoimmunity.
Interleukin-21, which is produced by activated natural killer T (NKT) cells and CD4+ T cells, exhibits pleiotropic effects not only on a variety of immune cells but also on non-immune cells. It has been demonstrated that IL-21 plays significant roles in the process of autoimmune diseases and inflammatory diseases.
The aim of this study was to evaluate serum 25 (HO)D, serum IL-21 and correlation between 25(HO)D and IL-21 in vitiligo patients in comparison of normal controls, also statistical analysis of all data obtained.
In this study, the serum 25 (OH)D and serum IL-21 levels were examined in 21 patients with vitiligo compared to 21 genders and age matched healthy controls.