Most of these associated genes participate in important pathways involved in the pathogenesis of vitiligo. More than 40 robust susceptible loci have been identified and confirmed to be associated with vitiligo by using GWAS. Recently, our understanding of the genetic basis of vitiligo has been rapidly advancing through genome-wide association study (GWAS). ![]() Previously, vitiligo susceptibility genes were mainly revealed through linkage analysis and candidate gene studies. Genetic factors are known to play key roles in vitiligo through discoveries in association studies and family studies. Vitiligo is an autoimmune disease with a strong genetic component, characterized by areas of depigmented skin resulting from loss of epidermal melanocytes. Shen, Changbing Gao, Jing Sheng, Yujun Dou, Jinfa Zhou, Fusheng Zheng, Xiaodong Ko, Randy Tang, Xianfa Zhu, Caihong Yin, Xianyong Sun, Liangdan Cui, Yong Zhang, Xuejun Genetic Susceptibility to Vitiligo: GWAS Approaches for Identifying Vitiligo Susceptibility Genes and Loci While many of the specific biologic mechanisms through which these genetic factors operate to cause vitiligo remain to be elucidated, it is now clear that vitiligo is an autoimmune disease involving a complex relationship between programming and function of the immune system, aspects of the melanocyte autoimmune target, and dysregulation of the immune response. For this last group, there appears to be an opposite relationship between susceptibility to vitiligo and susceptibility to melanoma, suggesting that vitiligo may engage a normal mechanism of immune surveillance for melanoma. A large fraction of these genes encode proteins involved in immune regulation, a number of others play roles in cellular apoptosis, and still others are involved in regulating functions of melanocytes. At many of these vitiligo susceptibility loci the corresponding relevant genes have now been identified, and for some of these genes the specific DNA sequence variants that contribute to vitiligo risk are also now known. Large-scale genome-wide association studies, principally in European-derived whites and in Chinese, have discovered approximately 50 different genetic loci that contribute to vitiligo risk, some of which also contribute to other autoimmune diseases that are epidemiologically associated with vitiligo. Synopsis Vitiligo is “complex disorder†(also termed polygenic and multifactorial), reflecting simultaneous contributions of multiple genetic risk factors and environmental triggers. Although the vitiligo-melasma group with truncal lesions started repigmenting earlier, the final pigmentation was more extensive in the vitiligo group. Unexpectedly, for truncal lesions, patients with vitiligo alone responded better than those with both conditions. Patients having both vitiligo and melasma have a significantly better prognosis for repigmentation on the face and limbs with narrow-band UVB compared with patients with vitiligo alone the vitiligo-melasma patients achieve repigmentation much earlier and also attain a greater level of repigmentation. On the trunk, only 20% of vitiligo-melasma patients showed ≥75% pigmentation at 12 weeks compared with 63% of patients in the vitiligo group. Over the limbs, 73% of patients in the vitiligo-melasma group attained 75% or more pigmentation at the end of 12 weeks compared with only 9% in the vitiligo group. ![]() At the end of 12 weeks, 86% of patients in the vitiligo-melasma group attained ≥75% pigmentation on the face, whereas this was achieved in only 12.5% of patients in the vitiligo group. Patients in both groups were treated with narrow-band UVB and a comparison of the zonal repigmentation was made at 4, 8, and 12 weeks after the initiation of therapy. To evaluate and compare the response to narrow-band UVB in a group of patients with vitiligo, and another group of patients with vitiligo and coexisting melasma ( vitiligo-melasma). ![]() A small subset of vitiligo patients paradoxically also have melasma. Melasma, a hyperpigmentary disorder, presents as irregular, brown, macular hypermelanosis. Vitiligo is the most common depigmentary disorder of the skin and hair, resulting from selective destruction of melanocytes. Sharma, Parikshit Pai, Harsha S Pai, Ganesh S Kuruvila, Maria Kolar, Reshma Response to narrow-band UVB- vitiligo-melasma versus vitiligo: a comparative study.
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