title: Tumor necrosis factor-α and -β genetic polymorphisms as a risk factor in Saudi patients with vitiligo.
abstract: Vitiligo is an acquired depigmentary disorder of the skin, characterized by multiple susceptibility loci and genetic heterogeneity. The etiology of vitiligo is unknown but several hypotheses, including an autoimmune origin, have been proposed. Tumor necrosis factor (TNF)-α, a pleiotropic proinflammatory cytokine, has been shown to play a critical role in several autoimmune diseases including vitiligo. The aim of present study was to determine the association of TNF-α and -β gene polymorphisms with vitiligo in Saudi patients. TNF-α and -β genes were amplified in 123 Saudi patients and 200 matched controls using polymerase chain reaction to search for polymorphisms involved at positions -308, and intron 1 +252. The frequency of the TNF-α (-308) GA genotype was higher and the frequencies of the GG and AA genotypes were significantly lower in vitiligo patients compared to controls. These findings suggested that genotype GA-positive individuals at position -308 of TNF-α are susceptible to vitiligo, whereas the GG and AA genotypes might exert a protective effect. The frequency of allele A (TNF-α 2-allele) was significantly higher and that of allele G (TNF-α 1-allele) was lower in vitiligo patients compared to controls, indicating an association of allele A with susceptibility to vitiligo in Saudi patients. The results of our examination of TNF-β (intron 1 +252) polymorphisms showed a significant increase in the frequency of the GG genotype and allele G (TNF-β 1-allele) in vitiligo patients, suggesting a susceptibility of the GG genotype and allele G for vitiligo. By contrast, the high frequency of the GA genotype in controls might indicate a protective effect. The results of the present study strongly support a link between TNF-α (-308) and -β (intron 1 +252) polymorphisms and vitiligo in Saudi patients.
authors.affiliation: Department of Dermatology, Riyadh Military Hospital, Riyadh, Saudi Arabia.
authors.forename: F
authors.initials: F
authors.lastname: Al-Harthi
authors.forename: A
authors.initials: A
authors.lastname: Zouman
authors.forename: M
authors.initials: M
authors.lastname: Arfin
authors.forename: M
authors.initials: M
authors.lastname: Tariq
authors.forename: A
authors.initials: A
authors.lastname: Al-Asmari
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006801:Humans; D007438:Introns; D008233:Lymphotoxin-alpha / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012529:Saudi Arabia; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D014820:Vitiligo / Q000235:genetics*
chemical_list: D008233:Lymphotoxin-alpha; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha