biostudies-literatureHayashi MHHS | National Institutes of HealthNIAMS NIH HHS1357-62https://www.ebi.ac.uk/biostudies/studies/S-EPMC4747738biostudies-literatureUnknown113(5)HLA-A is a class I major histocompatibility complex receptor that presents peptide antigens on the surface of most cells. Vitiligo, an autoimmune disease in which skin melanocytes are destroyed by cognate T cells, is associated with variation in the HLA-A gene; specifically HLA-A*02:01, which presents multiple vitiligo melanocyte autoantigens. Refined genetic mapping localizes vitiligo risk in the HLA-A region to an SNP haplotype ∼20-kb downstream, spanning an ENCODE element with many characteristics of a transcriptional enhancer. Convergent CTCF insulator sites flanking the HLA-A gene promoter and the predicted transcriptional regulator, with apparent interaction between these sites, suggests this element regulates the HLA-A promoter. Peripheral blood mononuclear cells from healthy subjects homozygous for the high-risk haplotype expressed 39% more HLA-A RNA than cells from subjects carrying nonhigh-risk haplotypes (P = 0.0048). Similarly, RNAseq analysis of 1,000 Genomes Project data showed more HLA-A mRNA expressed in subjects homozygous for the high-risk allele of lead SNP rs60131261 than subjects homozygous for the low-risk allele (P = 0.006). Reporter plasmid transfection and genomic run-on sequence analyses confirm that the HLA-A transcriptional regulator contains multiple bidirectional promoters, with greatest activity on the high-risk haplotype, although it does not behave as a classic enhancer. Vitiligo risk associated with the MHC class I region thus derives from combined quantitative and qualitative phenomena: a SNP haplotype in a transcriptional regulator that induces gain-of-function, elevating expression of HLA-A RNA in vivo, in strong linkage disequilibrium with an HLA-A allele that confers *02:01 specificity.Proceedings of the National Academy of Sciences of the United States of AmericaAutoimmune vitiligo is associated with gain-of-function by a transcriptional regulator that elevates expression of HLA-A*02:01 in vivo.PMC4747738R01 AR045584R01 AR056292R01AR056292R01AR045584Yorgov DFerrara TMCavalli GSpritz RAHagman JJones KLJin YSantorico SAHayashi MDinarello CAfalseAutoimmune vitiligo is associated with gain-of-function by a transcriptional regulator that elevates expression of HLA-A*02:01 in vivo.HLA-A is a class I major histocompatibility complex receptor that presents peptide antigens on the surface of most cells. Vitiligo, an autoimmune disease in which skin melanocytes are destroyed by cognate T cells, is associated with variation in the HLA-A gene; specifically HLA-A*02:01, which presents multiple vitiligo melanocyte autoantigens. Refined genetic mapping localizes vitiligo risk in the HLA-A region to an SNP haplotype ∼20-kb downstream, spanning an ENCODE element with many characteristics of a transcriptional enhancer. Convergent CTCF insulator sites flanking the HLA-A gene promoter and the predicted transcriptional regulator, with apparent interaction between these sites, suggests this element regulates the HLA-A promoter. Peripheral blood mononuclear cells from healthy subjects homozygous for the high-risk haplotype expressed 39% more HLA-A RNA than cells from subjects carrying nonhigh-risk haplotypes (P = 0.0048). Similarly, RNAseq analysis of 1,000 Genomes Project data showed more HLA-A mRNA expressed in subjects homozygous for the high-risk allele of lead SNP rs60131261 than subjects homozygous for the low-risk allele (P = 0.006). Reporter plasmid transfection and genomic run-on sequence analyses confirm that the HLA-A transcriptional regulator contains multiple bidirectional promoters, with greatest activity on the high-risk haplotype, although it does not behave as a classic enhancer. Vitiligo risk associated with the MHC class I region thus derives from combined quantitative and qualitative phenomena: a SNP haplotype in a transcriptional regulator that induces gain-of-function, elevating expression of HLA-A RNA in vivo, in strong linkage disequilibrium with an HLA-A allele that confers *02:01 specificity.2016-01-01T00:00:00Z2016 Feb2025-04-26T22:42:57.006Z2019-03-27T02:08:47ZS-EPMC47477382678788610.1073/pnas.1525001113