Analysis of inducible nitric oxide synthase gene polymorphisms in vitiligo in Han Chinese people

Abstract

Background: Vitiligo is a chronic depigmented skin disorder with regional melanocytes depletion. The pathogenesis was not completely clarified. Recently, more and more evidence suggested that polymorphisms of some genes are associated with vitiligo risk. Here, we want to examine the association between the inducible nitric oxide synthase (iNOS) gene polymorphisms and the risk of vitiligo in Chinese populations.

Methods and principal findings: In a hospital-based case-control study of 749 patients with vitiligo and 763 age- and sex-matched healthy controls, three polymorphisms of iNOS gene were genotyped by using the PCR-restriction fragment length polymorphism (PCR-RFLP) and mutagenically separated PCR (MS-PCR) methods, respectively. We found the iNOS-954 polymorphism was associated with a significantly higher risk of vitiligo (adjusted OR = 1.36, 95% CI = 1.02-1.81). Furthermore, this association is more pronounced in vulgaris vitiligo, active vitiligo and vitiligo without other autoimmune diseases in the stratification study. Analysis of haplotypes showed increased risk for the C₋₁₁₇₃C₋₉₅₄C(Ex₁₆+₁₄) (OR = 1.44, 95% CI = 1.01-1.74). In addition, the serum iNOS activity is significantly associated with iNOS-954 combined genotype (GC+CC) and is much higher in vitiligo patients than in the controls (P<0.01). Logistic regression analysis of iNOS activity showed increased risk between higher activity and iNOS-954 G→C variant genotype carriers (P(trend)<0.001).

Conclusions and significance: INOS gene polymorphisms may play an important role in the genetic susceptibility to the development of vitiligo.

Figure 1. Serum iNOS activity and correlations to vitiligo genetype.

(A) The serum iNOS activity in vitiligo patients' group is significantly higher than that in the normal control group (P<0.01). (B) Compared with the iNOS–954 protective genotype GG group, the risk genotype (GC+CC) group has the higher serum iNOS activity (P<0.01).