Several lines of evidence have implicated the gene encoding cytotoxic T lymphocyte antigen 4 (polymorphisms and vitiligo have yielded conflicting results. and indeed may be secondary, driven by primary genetic association of with other autoimmune diseases that are epidemiologically associated with vitiligo. (gene encodes cytotoxic T lymphocyte antigen 4, a key negative feedback regulator of T-cell activation and proliferation during the immune response (Brand et al., 2005; Gough et al., 2005). Variation in has been genetically associated with a number of autoimmune diseases, typically at an effect size (odds ratio; OR) of about 1.5 to 2.0 (Brand et al., 2005; Gough et al., 2005; Kavvoura et al., 2007). However, studies of genetic association between and vitiligo have yielded conflicting results. An initial study 148741-30-4 manufacture of a single microsatellite in United Kingdom (UK) Caucasian (CEU) patients reported genetic association principally in patients with other autoimmune diseases (Kemp et al., 1999). Similar findings were reported in a very small study of Turkish patients (Itirli et al., 2005). A subsequent study of UK CEU patients observed association of single-nucleotide polymorphisms (SNPs) only in those vitiligo patients who had other concomitant autoimmune diseases (Blomhoff et al., 2005). In contrast, in a large 148741-30-4 manufacture family-based association study of USA and UK CEU families with generalized vitiligo and other C10rf4 vitiligo-associated autoimmune diseases we found no genetic association with SNPs (Laberge et al., 2008). Here, we describe two additional genetic association studies of SNPs with generalized vitiligo, in two independent Romanian CEU case-control cohorts. Neither individual study showed any evidence of association of with generalized vitiligo, either in the total patient group or in the subgroup of patients who had other concomitant autoimmune diseases. To resolve the apparent conflicting results among the various genetic association studies of and vitiligo, we carried out a meta-analysis that combined these two new studies with the two other published association studies of SNPs with vitiligo in CEU cohorts. This meta-analysis provided much higher statistical power than any of the individual studies, but again showed no genetic association of SNPs with vitiligo overall. However, in the subgroup of vitiligo patients who had other concomitant autoimmune diseases there was significant association of SNP rs231775 and near-significance of several other SNPs in linkage disequilibrium (LD) with rs231775. Results and discussion We first carried out two independent case-control association studies of SNPs, in two independent Romanian case-control cohorts. The first Romanian cohort consisted of 66 unrelated CEU patients with generalized vitiligo (18 with other concomitant autoimmune diseases) and 85 unrelated CEU controls with no auto-immune diseases; details of this case-control cohort have been published previously (Jin et al., 2007). The second Romanian case-control cohort consisted of 101 unrelated CEU patients and 100 unrelated healthy CEU controls from the same geographical region. Among the 101 patients in the second cohort, 90 had vitiligo vulgaris, 9 acrofacial vitiligo, and 2 vitiligo universalis, and 32 (31.8%) also had other concomitant autoimmune diseases, including autoimmune thyroid disease (17), rheumatoid arthritis (5), adult-onset insulin-dependent diabetes (5), psoriasis (3), systemic lupus erythematosus (1), and alopecia areata (1). There were no signifi-cant differences of gender or age distributions among the patients (48.2 18.5) versus controls (47.8 18.7). In the first case-control cohort, we genotyped seven SNPs spanning 77 kb in the region of chromosome 2; six SNPs (rs1863800, rs231775, rs3087243, rs11571302, rs11571297, and rs10932037) were genotyped directly and one (rs231806) was imputed based on LD patterns (Marchini et al., 2007). None of these SNPs deviated from HardyCWeinberg equilibrium among the controls (not shown). None of these SNPs showed statistically significant (defined as nominal P-value <0.05) allelic (Table 1) or genotypic (not shown) association with generalized vitiligo in either the total patient group (n = 66) or in subgroups of patients 148741-30-4 manufacture who had (n = 18) or did not have (n 148741-30-4 manufacture = 48) other autoimmune diseases. No multiple testing correction was applied, given the lack of any apparant association. Six of the seven SNPs tested were in a single block of LD (D > 0.8), and we observed no significant association of SNP haplotypes with disease in any patient group (P = 0.15; not shown). Table 1 Allelic.