Generalized vitiligo is the most common pigmentation disorder, the result of
Generalized vitiligo is the most common pigmentation disorder, the result of autoimmune loss of melanocytes from the skin and hair, with a high frequency of other autoimmune diseases in vitiligo patients and their relatives. association signals. INTRODUCTION Generalized vitiligo is an acquired, non-contagious disorder, in which progressive, patchy loss of pigmentation from the skin, overlying hair, and oral mucosa results from autoimmune loss of melanocytes from the involved areas (Nordlund (NACHT leucine-rich-repeat protein) (Jin (Alkhateeb = 6.07 10?6) for the 1032754-81-6 IC50 total 102 families and 4.01 (= 1.52 10?6) for the 51 vitiligo-autoimmune disease families; the LOD maximum was located at 89.4 cM and the 1-LOD interval spanned B33.3 cM in 7q21. Similarly, a locus on chromosome 9, which previously showed only suggestive evidence for linkage in the total 102 vitiligo families (Spritz = 2.24 10?4) for the total 102 families and 3.18 (= 6.35 10?5) xfor the 51 vitiligoautoimmune disease families; the LOD maximum was at 88.1 cM and the 1-LOD interval spanned ~17.7 cM in 9q12-q22. In contrast, support for putative 1032754-81-6 IC50 vitiligo susceptibility loci on chromosomes 8, 13, 19, and 22 was reduced substantially, below the threshold for suggestive linkage (LOD 1.9); accordingly, these three signals were not pursued further. Family-based association studies To refine localization of the chromosome 7 and 9 vitiligo-autoimmunity susceptibility loci, we next carried out family-based association analyses of high-density SNPs genotyped through the 1-LOD linkage intervals. We genotyped 333 members of the aforementioned 51 vitiligo-autoimmune disease families for 867 SNPs 1032754-81-6 IC50 spanning the chromosome 7 linkage region and 304 SNPs spanning the chromosome 9 linkage region, respectively, capturing 38.6 and 27.2% of the common variation (minor allele frequency >0.1, on chromosome 17p that we identified previously (tagged by rs6502867 and rs4790797) (Jin variants in these families (Jin = 0.0003, respectively) and the expanded =autoimmune disease phenotype (Table 6, = 0.0005 and = 0.0015 and = 0.0011, respectively), and the P-value for chromosome 9 SNP rs4744411 on the expanded autoimmune disease phenotype was very close to significant (Table 6, = 0.0036). Although = 0.0141 for vitiligo, = 0.1012 for the expanded autoimmune disease phenotype), there was suggestive evidence of a two-way interaction between rs6960920 and SNP rs6502867 (Table 5, = 0.0019; nominal significance threshold = 0.0017), as well as a significant three-way interaction between chromosome 7 SNPs rs6960920 and 1032754-81-6 IC50 rs734930 and SNP rs6502867 (Table 5, = 0.0009) for the vitiligo phenotype, and a significant three-way interaction between chromosome 7p SNP rs6960920, chromosome 9 SNP rs4744411, and SNP rs6502867 for both vitiligo (Table 5, = 0.0012) and the expanded autoimmune disease phenotype (Table 6, = 0.0006). Table 5 Wald tests of interactions for Cd14 the generalized vitiligo phenotype using an interaction testing framework Table 6 Wald tests of 1032754-81-6 IC50 interactions for the expanded autoimmune disease phenotype using an interaction testing framework DISCUSSION We have carried out a high-density SNP association study across regions of genetic linkage we previously detected on chromosome 7 and 9 for generalized vitiligo, an autoimmune disease of skin depigmentation. The family-based nature of the study makes the results robust against false-positive associations from cryptic population stratification. The linkage results suggested that loci in these regions might contribute to both generalized vitiligo and to a broader autoimmunity phenotype. Three signals, tagged by SNPs rs6960920 in 7p13, rs734930 in 7q11, and rs4744411 in 9q22, were significantly associated with generalized vitiligo as well as with a broader autoimmunity phenotype that included vitiligo and other autoimmune diseases commonly associated with vitiligo. These three SNPs also showed significant interactions with SNP rs6502867, which we previously showed to be associated with vitiligo and other autoimmune diseases in these families (Jin and and 5 kb 3 to encodes an apparent member of the serine/threonine protein kinase and Ca(2+)/calmodulin-dependent protein kinase subfamilies that has an essential role in PAF-induced.