RESUMO
The psoriasis susceptibility locus 1 (PSORS1) mutation is assumed to reside within a region around human leukocyte antigen-C spanning 250 kb, termed risk haplotype (RH) 1/2. By re-analyzing a published data set with a previously developed method, the haplotype sharing statistic, we confirm localization of PSORS1 to the RH1 region and refine its location to marker M6S168. We replicate this result in an independent patient sample. The target region harbors fragments of a human endogenous retrovirus K (HERV-K) endogenous retrovirus. Two single-nucleotide polymorphisms with alleles differing between high- and low-risk haplotypes are located within the HERV-K dUTPase. One of these encodes a predicted non-conserved Glu-Arg exchange. The HERV-K dUTPase is expressed in peripheral blood and in normal as well as lesional psoriatic skin. Our results indicate that an endogenous retroviral dUTPase constitutes a candidate gene for the PSORS1 mutation.
Assuntos
Cromossomos Humanos Par 6 , Retrovirus Endógenos/genética , Psoríase/genética , Pirofosfatases/genética , Predisposição Genética para Doença/genética , Antígenos HLA-C/genética , Haplótipos , Humanos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Type 1 interferon can trigger flares of psoriasis. Hypersensitivity to type 1 interferon signaling causes a psoriasis-like skin disease in mice deficient for the transcription factor interferon regulatory factor 2 (IRF2). The human IRF2 gene is located at a previously identified candidate psoriasis susceptibility locus on chromosome 4q (PSORS3 at D4S1535). Therefore, we tested association of psoriasis with IRF2. We generated a sample consisting of 157 families with a total of 521 individuals. Five novel microsatellite markers were developed and typed, and complemented with three known markers to yield a set of eight markers spaced within 600 kb around the IRF2 gene, three of which are located in the gene. We detected association of IRF2 with type 1 psoriasis at two markers in the IRF2 gene. Haplotype sharing analysis confirmed association of IRF2 with type 1 psoriasis (p=0.0017; pcorr=0.03). The 921G/A SNP in exon 9 was found to obliterate a predicted exon splice enhancer in an allele-specific manner. There was a suggestive increase of homozygosity for the splicing-deficient allele in type 1 psoriasis patients. Our data identify IRF2 as a potential susceptibility gene for psoriasis.
Assuntos
Proteínas de Ligação a DNA/genética , Psoríase/genética , Proteínas Repressoras , Fatores de Transcrição , Éxons , Predisposição Genética para Doença , Haplótipos , Humanos , Fator Regulador 2 de Interferon , Repetições de Microssatélites , Polimorfismo de Nucleotídeo Único , Splicing de RNA/genéticaRESUMO
Multiple-synostosis syndrome is an autosomal dominant disorder characterized by progressive symphalangism, carpal/tarsal fusions, deafness, and mild facial dysmorphism. Heterozygosity for functional null mutations in the NOGGIN gene has been shown to be responsible for the disorder. However, in a cohort of six probands with multiple-synostosis syndrome, only one was found to be heterozygous for a NOGGIN mutation (W205X). Linkage studies involving the four-generation family of one of the mutation-negative patients excluded the NOGGIN locus, providing genetic evidence of locus heterogeneity. In this family, polymorphic markers flanking the GDF5 locus were found to cosegregate with the disease, and sequence analysis demonstrated that affected individuals in the family were heterozygous for a novel missense mutation that predicts an R438L substitution in the GDF5 protein. Unlike mutations that lead to haploinsufficiency for GDF5 and produce brachydactyly C, the protein encoded by the multiple-synostosis-syndrome allele was secreted as a mature GDF5 dimer. These data establish locus heterogeneity in multiple-synostosis syndrome and demonstrate that the disorder can result from mutations in either the NOGGIN or the GDF5 gene.