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Objective: To determine whether systemic juvenile idiopathic arthritis (JIA) susceptibility loci that were identified by candidate gene studies demonstrate association with systemic JIA in the largest study population assembled to date., Methods: Single-nucleotide polymorphisms (SNPs) from 11 previously reported systemic JIA risk loci were examined for association in 9 populations, including 770 patients with systemic JIA and 6,947 controls. The effect of systemic JIA-associated SNPs on gene expression was evaluated in silico in paired whole genome and RNA sequencing data from the lymphoblastoid cell lines (LCLs) of 373 European subjects from the 1000 Genomes Project. Responses of systemic JIA-associated SNPs to anakinra treatment were evaluated in 38 US patients for whom treatment response data were available., Results: We found no association between the previously reported 26 SNPs and systemic JIA. Expanded analysis of the regions containing the 26 SNPs revealed only 1 significant association: the promoter region of IL1RN (P < 1 × 10 -4 ). Systemic JIA-associated SNPs correlated with IL1RN expression in LCLs, with an inverse correlation between systemic JIA risk and IL1RN expression. The presence of homozygous IL1RN high expression alleles correlated strongly with a lack of response to anakinra therapy (odds ratio 28.7 [95% confidence interval 3.2-255.8])., Conclusion: In our study, IL1RN was the only candidate locus associated with systemic JIA. The implicated SNPs are among the strongest known determinants of IL1RN and interleukin-1 receptor antagonist levels, linking low expression with increased systemic JIA risk. Homozygous high expression alleles predicted nonresponsiveness to anakinra therapy, making them ideal candidate biomarkers to guide systemic JIA treatment. This study is an important first step toward the personalized treatment of systemic JIA., (© 2018, American College of Rheumatology.)

Background: The genetic contributions to pediatric onset ulcerative colitis (UC), characterized by severe disease and extensive colonic involvement, are largely unknown. In adult onset UC, Genome Wide Association Study (GWAS) has identified numerous loci, most of which have a modest susceptibility risk (OR 0.84-1.14), with the exception of the human leukocyte antigen (HLA) region on Chromosome 6 (OR 3.59)., Method: To study the genetic contribution to exclusive pediatric onset UC, a GWAS was performed on 466 cases with 2099 healthy controls using UK Biobank array. SNP2HLA was used to impute classical HLA alleles and their corresponding amino acids, and the results are compared with adult onset UC., Results: HLA explained the almost entire association signal, dominated with 191 single nucleotide polymorphisms (SNPs) (p = 5 x 10-8 to 5 x 10-10). Although very small effects, established SNPs in adult onset UC loci had similar direction and magnitude in pediatric onset UC. SNP2HLA imputation identified HLA-DRB1*0103 (odds ratio [OR] = 6.941, p = 1.92*10-13) as the most significant association for pediatric UC compared with adult onset UC (OR = 3.59). Further conditioning showed independent effects for HLA-DRB1*1301 (OR = 2.25, p = 7.92*10-9) and another SNP rs17188113 (OR = 0.48, p = 7.56*10-9). Two HLA-DRB1 causal alleles are shared with adult onset UC, while at least 2 signals are unique to pediatric UC. Subsequent stratified analyses indicated that HLA-DRB1*0103 has stronger association for extensive disease (E4: OR = 8.28, p = 4.66x10-10) and female gender (OR = 8.85, p = 4.82x10-13)., Conclusion: In pediatric onset UC, the HLA explains almost the entire genetic associations. In addition, the HLA association is approximately twice as strong in pediatric UC compared with adults, due to a combination of novel and shared effects. We speculate the paramount importance of antigenic stimulation either by infectious or noninfectious stimuli as a causal event in pediatric UC onset.

Purpose: Variants in the gene encoding Programmed Cell Death-1 (PDCD1) have been associated with susceptibility to Systemic Lupus Erythematosus and other autoimmune diseases. Given that clinically distinct autoimmune phenotypes share common genetic susceptibility factors, variants in PDCD-1 were tested for a possible association with Juvenile Idiopathic Arthritis (JIA)., Methods: Four Single Nucleotide Polymorphisms (SNPS) in the PDCD1 gene were genotyped and analyzed: rs7421861, rs11568821, rs10204525, and rs7568402 in 834 cases and 855 controls of Northern European ancestry. Each variant was examined for possible associations with JIA and then analyzed for association with JIA categories., Results: PDCD1 variants showed no association with JIA in the cohort overall (rs7421861 p=0.63, rs11568821 p=0.13, rs10204525 p=0.31, and rs7568402 p=0.45). Stratification by JIA categories indicated a significant association between systemic JIA and PDCD1 rs7568402 (OR=0.53, p=0.0027), which remained significant after 10,000 permutations, but was not replicated in an independent multi-ethnic systemic JIA cohort. A nominal association between enthesitis-related arthritis and rs115668821 was also observed (OR=0.22, p=0.012)., Conclusion: Unlike other multiple autoimmune disease associated genetic variants, there was no association between PDCD1 variants and JIA or JIA categories., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Systemic juvenile idiopathic arthritis (sJIA) is an often severe, potentially life-threatening childhood inflammatory disease, the pathophysiology of which is poorly understood. To determine whether genetic variation within the MHC locus on chromosome 6 influences sJIA susceptibility, we performed an association study of 982 children with sJIA and 8,010 healthy control subjects from nine countries. Using meta-analysis of directly observed and imputed SNP genotypes and imputed classic HLA types, we identified the MHC locus as a bona fide susceptibility locus with effects on sJIA risk that transcended geographically defined strata. The strongest sJIA-associated SNP, rs151043342 [P = 2.8 × 10(-17), odds ratio (OR) 2.6 (2.1, 3.3)], was part of a cluster of 482 sJIA-associated SNPs that spanned a 400-kb region and included the class II HLA region. Conditional analysis controlling for the effect of rs151043342 found that rs12722051 independently influenced sJIA risk [P = 1.0 × 10(-5), OR 0.7 (0.6, 0.8)]. Meta-analysis of imputed classic HLA-type associations in six study populations of Western European ancestry revealed that HLA-DRB1*11 and its defining amino acid residue, glutamate 58, were strongly associated with sJIA [P = 2.7 × 10(-16), OR 2.3 (1.9, 2.8)], as was the HLA-DRB1*11-HLA-DQA1*05-HLA-DQB1*03 haplotype [6.4 × 10(-17), OR 2.3 (1.9, 2.9)]. By examining the MHC locus in the largest collection of sJIA patients assembled to date, this study solidifies the relationship between the class II HLA region and sJIA, implicating adaptive immune molecules in the pathogenesis of sJIA.

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthropathy of childhood. Juvenile idiopathic arthritis is believed to be a complex genetic trait influenced by both genetic and environmental factors. Twin and family studies suggest a substantial role for genetic factors in the predisposition to JIA. Describing the genetics is complicated by the heterogeneity of JIA; the International League of Associations for Rheumatology (ILAR) has defined seven categories of JIA based on distinct clinical and laboratory features. Utilizing a variety of techniques including candidate gene studies, the use of genotyping arrays such as Immunochip, and genome wide association studies (GWAS), both human leukocyte antigen (HLA) and non-HLA susceptibility loci associated with JIA have been described. Several of these polymorphisms (e.g. HLA class II, PTPN22, STAT4) are shared with other common autoimmune conditions; other novel polymorphisms that have been identified may be unique to JIA. Associations with oligoarticular and RF-negative polyarticular JIA are the best characterized. A strong association between HLA DRB1:11:03/04 and DRB1:08:01, and a protective effect of DRB1:15:01 have been described. HLA DPB1:02:01 has also been associated with oligoarticular and RF-negative polyarticular JIA. Besides PTPN22, STAT4 and PTPN2 variants, IL2, IL2RA, IL2RB, as well as IL6 and IL6R loci also harbor variants associated with oligoarticular and RF-negative polyarticular JIA. RF-positive polyarticular JIA is associated with many of the shared epitope encoding HLA DRB1 alleles, as well as PTPN22, STAT4 and TNFAIP3 variants. ERA is associated with HLA B27. Most other associations between JIA categories and HLA or non-HLA variants need confirmation. The formation of International Consortia to ascertain and analyze large cohorts of JIA categories, validation of reported findings in independent cohorts, and functional studies will enhance our understanding of the genetic underpinnings of JIA., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objective: Children with childhood-onset rheumatoid arthritis (RA) include those with rheumatoid factor or anti-citrullinated protein antibody-positive juvenile idiopathic arthritis. To test the hypothesis that adult-onset RA-associated variants are also associated with childhood-onset RA, we investigated RA-associated variants at 5 loci in a cohort of patients with childhood-onset RA. We also assessed the cumulative association of these variants in susceptibility to childhood-onset RA using a weighted genetic risk score (wGRS)., Methods: A total of 155 children with childhood-onset RA and 684 healthy controls were genotyped for 5 variants in the PTPN22, TRAF1/C5, STAT4, and TNFAIP3 loci. High-resolution HLA-DRB1 genotypes were available for 149 cases and 373 controls. We tested each locus for association with childhood-onset RA via logistic regression. We also computed a wGRS for each subject, with weights based on the natural log of the published odds ratios (ORs) for the alleles investigated, and used logistic regression to test the wGRS for association with childhood-onset RA., Results: Childhood-onset RA was associated with TNFAIP3 rs10499194 (OR 0.60 [95% confidence interval 0.44-0.83]), PTPN22 rs2476601 (OR 1.61 [95% confidence interval 1.11-2.31]), and STAT4 rs7574865 (OR 1.41 [95% confidence interval 1.06-1.87]) variants. The wGRS was significantly different between cases and controls (P < 2 × 10(-16) ). Individuals in the third to fifth quintiles of wGRS had a significantly increased disease risk compared to baseline (individuals in the first quintile). Higher wGRS was associated with increased risk of childhood-onset RA, especially among males., Conclusion: The magnitude and direction of the association between TNFAIP3, STAT4, and PTPN22 variants and childhood-onset RA are similar to those observed in RA, suggesting that adult-onset RA and childhood-onset RA share common genetic risk factors. Using a wGRS, we have demonstrated the cumulative association of RA-associated variants with susceptibility to childhood-onset RA., (Copyright © 2013 by the American College of Rheumatology.)

Objective: In a genome-wide association study of Caucasian patients with juvenile idiopathic arthritis (JIA), we have previously described findings limited to autoimmunity loci shared by JIA and other diseases. The present study was undertaken to identify novel JIA-predisposing loci using genome-wide approaches., Methods: The discovery cohort consisted of Caucasian JIA cases (n = 814) and local controls (n = 658) genotyped on the Affymetrix Genome-Wide SNP 6.0 Array, along with 2,400 out-of-study controls. In a replication study, we genotyped 10 single-nucleotide polymorphisms (SNPs) in 1,744 cases and 7,010 controls from the US and Europe., Results: Analysis within the discovery cohort provided evidence of associations at 3q13 within C3orf1 and near CD80 (rs4688011) (odds ratio [OR] 1.37, P = 1.88 × 10(-6) ) and at 10q21 near JMJD1C (rs647989 [OR 1.59, P = 6.1 × 10(-8) ], rs12411988 [OR 1.57, P = 1.16 × 10(-7) ], and rs10995450 [OR 1.31, P = 6.74 × 10(-5) ]). Meta-analysis provided further evidence of association for these 4 SNPs (P = 3.6 × 10(-7) for rs4688011, P = 4.33 × 10(-5) for rs6479891, P = 2.71 × 10(-5) for rs12411988, and P = 5.39 × 10(-5) for rs10995450). Gene expression data on 68 JIA cases and 23 local controls showed cis expression quantitative trait locus associations for C3orf1 SNP rs4688011 (P = 0.024 or P = 0.034, depending on the probe set) and JMJD1C SNPs rs6479891 and rs12411988 (P = 0.01 or P = 0.04, depending on the probe set and P = 0.008, respectively). Using a variance component liability model, it was estimated that common SNP variation accounts for approximately one-third of JIA susceptibility., Conclusion: Genetic association results and correlated gene expression findings provide evidence of JIA association at 3q13 and suggest novel genes as plausible candidates in disease pathology., (Copyright © 2012 by the American College of Rheumatology.)

Objective: Associations between shared epitope (SE)-encoding HLA-DRB1 alleles and rheumatoid arthritis (RA) are well established. However, only a limited number of studies have investigated these alleles in patients with childhood-onset RA, which is defined as rheumatoid factor- and/or anti-citrullinated protein antibody-positive juvenile idiopathic arthritis. The aims of this study were to investigate the largest cohort of patients with childhood-onset RA for association with SE alleles and to determine whether there is a hierarchy of risk based on the amino acid sequence of the SE., Methods: High-resolution HLA-DRB1 genotypes were obtained for 204 patients with childhood-onset RA and 373 healthy control subjects. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for different SE-encoding HLA-DRB1 alleles. In addition, genotype ORs were calculated for combinations of SE alleles classified into S(2) , S(3P) , or L alleles, based on amino acid sequences in position 70-74 of the DRβ1 chain, as proposed by Tezenas du Montcel et al., Results: We confirmed associations between HLA-DRB1 SE alleles and childhood-onset RA (76% of patients carried 1 or 2 SE alleles compared with 46% of control subjects; OR 3.81, 95% CI 2.4-6.0, P < 1 × 10(-7) ). We also observed associations between individual SE alleles (HLA-DRB1*0101, *0401, *0404, *0405, *0408, and *1001) and childhood-onset RA. Genotype-specific risk estimates suggested a hierarchy of risk, with the highest risk among individuals heterozygous for S(2) /S(3P) (OR 22.3, 95% CI 9.9-50.5, P < 0.0001)., Conclusion: We confirm the association between SE-encoding HLA-DRB1 alleles and susceptibility to childhood-onset RA. The excess risk conferred by carriage of the combination of S(2) and S(3P) risk alleles suggests that children with DRβ1 chains containing the KRAA and QRRAA or RRRAA sequences are especially susceptible to RA., (Copyright © 2012 by the American College of Rheumatology.)

Many autoimmune diseases (ADs) share similar underlying pathology and have a tendency to cluster within families, supporting the involvement of shared susceptibility genes. To date, most of the genetic variants associated with systemic lupus erythematosus (SLE) susceptibility also show association with others ADs. ITGAM and its associated 'predisposing' variant (rs1143679, Arg77His), predicted to alter the tertiary structures of the ligand-binding domain of ITGAM, may play a key role for SLE pathogenesis. The aim of this study is to examine whether the ITGAM variant is also associated with other ADs. We evaluated case-control association between rs1143679 and ADs (N=18,457) including primary Sjögren's syndrome, systemic sclerosis, multiple sclerosis, rheumatoid arthritis, juvenile idiopathic arthritis, celiac disease, and type-1 diabetes. We also performed meta-analyses using our data in addition to available published data. Although the risk allele 'A' is relatively more frequent among cases for each disease, it was not significantly associated with any other ADs tested in this study. However, the meta-analysis for systemic sclerosis was associated with rs1143679 (p(meta)=0.008). In summary, this study explored the role of ITGAM in general autoimmunity in seven non-lupus ADs, and only found association for systemic sclerosis when our results were combined with published results. Thus ITGAM may not be a general autoimmunity gene but this variant may be specifically associated with SLE and systemic sclerosis., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Objective: We previously demonstrated that there is familial aggregation of juvenile idiopathic arthritis (JIA). Using a large JIA cohort, we sought to identify additional clusters of JIA cases and to calculate robust estimates of the relative risk (RR) of JIA in the siblings and cousins of JIA probands. We also estimated the population attributable risk (PAR) of familial factors in JIA., Methods: A probabilistic record-linking analysis was performed by matching the records of 862 patients with JIA with the records of approximately 7 million individuals in the Utah Population Database (UPDB), a computerized genealogic database. For each patient, 5 control subjects matched for birth year and sex were selected from the UPDB. Specialized software was used to test for familial aggregation of disease, to estimate the magnitude of familial risks, and to identify families at high risk of disease., Results: We identified 22 founders who had significantly more descendants with JIA than expected (5-13 descendants; P values ranged from <0.0001 to <0.008). The PAR of familial factors for JIA was approximately 13%. The RR of JIA in the siblings of patients was significantly increased (11.6, 95% confidence interval [95% CI] 4.9-27.5, P < 2.59 x 10(-8)). The RR of JIA in first cousins was also increased (5.82, 95% CI 2.5-13.8, P < 6.07 x 10(-5))., Conclusion: We have identified the largest sets of JIA pedigrees described to date. Approximately 13% of cases of JIA can be attributed to familial factors. Siblings and first cousins of probands with JIA have an increased risk of JIA. The observed decline in the magnitude of risk between siblings and cousins suggests that JIA is influenced by shared genetic factors.

Objective: Subtypes of juvenile idiopathic arthritis (JIA) share phenotypic features with other autoimmune disorders. We investigated several genetic variants associated with rheumatoid arthritis (RA) and other autoimmune disorders for association with JIA to test the hypothesis that clinically distinct phenotypes share common genetic susceptibility factors., Methods: Cases were 445 children with JIA, and controls were 643 healthy adults. Using the TaqMan assay, subjects were genotyped for 8 single-nucleotide polymorphisms in 7 loci including rs10499194 and rs6920220 in the TNFAIP3 locus, rs6679677 in the RSBN1 locus, rs17696736 in the C12orf30 locus, rs3761847 in the TRAF1/C5 locus, rs2104286 in the IL2RA locus, rs7574865 in the STAT4 locus, and rs2542151 in the PTPN2 locus. Alleles and genotypes were analyzed for association with JIA and JIA subtypes. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated., Results: The strongest associations with JIA risk or protection were observed for TNFAIP3 variants rs10499194 (OR 0.74 [95% CI 0.61-0.91], P < 0.004) and rs6920220 (OR 1.30 [95% CI 1.05-1.61], P = 0.015). We also observed associations between JIA and both STAT4 (OR 1.24 [95% CI 1.02-1.51], P = 0.029) and C12orf30 (OR 1.20 [95% CI 1.01-1.43], P = 0.041) variants. The PTPN2 variant rs2542151 deviated from Hardy-Weinberg equilibrium and was excluded from analyses. Variants in IL2RA, TRAF1/C5, and RSBN1 were not associated with JIA. After stratification by JIA subtype, the TNFAIP3 and C12orf30 variants were associated with oligoarticular JIA, while the STAT4 variant was associated primarily with polyarticular JIA., Conclusion: We have demonstrated associations between JIA and variants in the TNFAIP3, STAT4, and C12orf30 regions that have previously shown associations with other autoimmune diseases, including RA and systemic lupus erythematosus. Our results suggest that clinically distinct autoimmune phenotypes share common genetic susceptibility factors.

Psoriasis is a common immune-mediated disorder that affects the skin, nails and joints. To identify psoriasis susceptibility loci, we genotyped 438,670 SNPs in 1,409 psoriasis cases and 1,436 controls of European ancestry. We followed up 21 promising SNPs in 5,048 psoriasis cases and 5,041 controls. Our results provide strong support for the association of at least seven genetic loci and psoriasis (each with combined P < 5 x 10(-8)). Loci with confirmed association include HLA-C, three genes involved in IL-23 signaling (IL23A, IL23R, IL12B), two genes that act downstream of TNF-alpha and regulate NF-kappaB signaling (TNIP1, TNFAIP3) and two genes involved in the modulation of Th2 immune responses (IL4, IL13). Although the proteins encoded in these loci are known to interact biologically, we found no evidence for epistasis between associated SNPs. Our results expand the catalog of genetic loci implicated in psoriasis susceptibility and suggest priority targets for study in other auto-immune disorders.

Juvenile idiopathic arthritis (JIA) is an autoimmune (AI) disease characterized by chronic arthritis in children. Children with JIA have increased prevalence of other AI diseases. Furthermore, relatives of children with JIA have been shown to have an increased prevalence of AI diseases. Our objective was to determine if there were differences in the prevalence of AI diseases among maternal and paternal relatives of children with JIA. Information about AI diseases among all living first- and second-degree relatives was collected by structured interviews with families of 121 simplex JIA families, 23 multiplex JIA families, and 45 control families. Overall, the prevalence of AI diseases was significantly increased among maternal second-degree relatives of cases compared to that of maternal second-degree relatives of controls [14% vs. 4.3%; p < 0.001]. The prevalence of AI diseases among mothers of JIA cases was three times that of fathers [32.3% vs. 11.4%; p < 0.0001]. The prevalence of AI diseases among all maternal second-degree relatives of children with JIA was significantly higher than that of all paternal second-degree relatives [14% vs. 7.9%; p < 0.004]. Although additional paternal effects cannot be excluded, together these results demonstrate that maternal relatives of children with JIA have an increased prevalence of autoimmunity compared to paternal relatives, suggesting that there might be a maternal parent-of-origin effect in JIA.

Objective: To estimate the degree of familial aggregation of juvenile idiopathic arthritis (JIA), determine whether the aggregation of JIA and the aggregation of type 1 diabetes mellitus (type 1 DM) overlap, and identify multiplex JIA pedigrees., Methods: Records of individuals with JIA or type 1 DM were probabilistically linked with records in the Utah Population Database (UPDB), a large computerized family history database. For each case of JIA or type 1 DM, 10 matched controls or 5 matched controls, respectively, were selected. All familial relationships among cases of JIA or type 1 DM were established. A familial risk score was calculated for each subject. For various levels of familial exposure to JIA or type 1 DM, one's risk (odds ratio [OR]) of developing JIA or type 1 DM was established (cases compared with controls). Recurrence risks for JIA were computed for relatives of JIA cases compared with relatives of controls. Extended JIA families were identified from a list of common ancestors., Results: Records of a total of 443 patients were linked with the UPDB. Of these, 381 (86.0%) met criteria for JIA. An increased risk for JIA was observed among relatives of probands with JIA. The prevalence of type 1 DM among JIA cases was higher than the US prevalence of type 1 DM (P < 0.003). The recurrence risk for JIA was significantly elevated among first-degree relatives of cases with JIA (OR 30.4). The overall prevalence of JIA was 28/100,000. Four extended JIA pedigrees were identified., Conclusion: There is familial aggregation of JIA in the Intermountain West region of the US. We have demonstrated that multiplex JIA pedigrees can be identified using a genealogic database.

Purpose of Review: Juvenile idiopathic arthritis (JIA) refers to a collection of chronic arthritides in children, and the major subtypes of JIA are similar to the subtypes of juvenile rheumatoid arthritis (JRA). Several genetic variants influencing susceptibility to JIA have been identified, including genes encoding the HLA molecules, cytokines, and other modulators of immune responses. This review outlines the principles behind genetic studies and summarizes recent studies on the genetics of JIA., Recent Findings: Recent studies confirm the association/linkage between JIA and the HLA region and provide evidence for additional loci involved in susceptibility to JIA. Several studies suggest that polymorphisms in other candidate genes also influence susceptibility to JIA. In addition, some genetic variants seem to influence the phenotype of JIA. A genome-wide scan for JRA in 121 affected sibling pair families confirms that gene(s) in the HLA region influence susceptibility to JRA and identifies other chromosomal regions that possibly influence susceptibility to JRA or subtypes of JRA. Functional studies suggest that biologic markers could be useful in defining the phenotype of individuals with JIA. Familial studies and gene expression profiling are useful tools in the dissection of the genetic basis of JIA., Summary: Although there are challenges to the identification of genetic factors underlying complex diseases such as JIA, considerable progress has been made in JIA genetics. Candidate gene studies remain important to identify genetic variants with small to moderate effects on the JIA phenotype., (Copyright 2004 Lippincott Williams & Wilkins)

Objective: Juvenile rheumatoid arthritis (JRA) represents a heterogeneous group of disorders with a complex genetic component. A genome scan was performed to detect linkage to JRA in 121 families containing 247 affected children in North America (the JRA Affected Sibpair [ASP] Registry)., Methods: Genotype data collected for HLA-DR and 386 microsatellite markers were subjected to multipoint nonparametric linkage analysis. Following analysis of the entire set of families, additional analyses were performed after a priori stratification by disease onset type, age at onset, disease course, and selected HLA-DRB1 alleles., Results: Linkage of JRA to the HLA region was confirmed (logarithm of odds [LOD] score 2.26). Additional evidence supporting linkage of JRA was observed at 1p36 (D1S214; LOD 1.65), 19p13 (D19S216; LOD 1.72), and 20q13 (D20S100; LOD 1.75). For early-onset polyarticular disease, evidence of linkage was found at chromosome 7q11 (D7S502; LOD 3.47). For pauciarticular disease, evidence supporting linkage was observed on chromosome 19p13 (D19S216; LOD 2.98), the same marker that supported linkage to the "JRA" phenotype. Other regions supporting linkage with JRA disease subtype included 20q13, 4q24, 12q24, and Xp11. Stratification of families based on the presence of the HLA-DR8 allele in affected siblings resulted in significant linkage observed at 2p25 (D2S162/D2S305; LOD 6.0)., Conclusion: These data support the hypothesis that multiple genes, including at least 1 in the HLA region, influence susceptibility to JRA. These findings for JRA are consistent with findings for other autoimmune diseases and support the notion that common genetic regions contribute to an autoimmune phenotype.

Psoriasis is a common immune-mediated disorder that affects the skin, nails and joints. To identify psoriasis susceptibility loci, we genotyped 438,670 SNPs in 1,409 psoriasis cases and 1,436 controls of European ancestry. We followed up 21 promising SNPs in 5,048 psoriasis cases and 5,041 controls. Our results provide strong support for the association of at least seven genetic loci and psoriasis (each with combined P < 5 x 10(-8)). Loci with confirmed association include HLA-C, three genes involved in IL-23 signaling (IL23A, IL23R, IL12B), two genes that act downstream of TNF-alpha and regulate NF-kappaB signaling (TNIP1, TNFAIP3) and two genes involved in the modulation of Th2 immune responses (IL4, IL13). Although the proteins encoded in these loci are known to interact biologically, we found no evidence for epistasis between associated SNPs. Our results expand the catalog of genetic loci implicated in psoriasis susceptibility and suggest priority targets for study in other auto-immune disorders.