Polymorphisms in the PTPN22 region are associated with psoriasis of early onset

Molecular consideration relevant to the mechanism of the comorbidity between psoriasis and systemic lupus erythematosus (Review)

Systemic lupus erythematosus (SLE), a common autoimmune disease with a global incidence and newly diagnosed population estimated at 5.14 (range, 1.4-15.13) per 100,000 person-years and 0.40 million people annually, respectively, affects multiple tissues and organs; for example, skin, blood system, heart and kidneys. Accumulating data has also demonstrated that psoriasis (PS) can be a systemic inflammatory disease, which can affect organs other than the skin and occur alongside other autoimmune diseases, such as inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis and SLE. The current explanations for the possible comorbidity of PS and SLE include: i) The two diseases share susceptible gene loci; ii) they share a common IL-23/T helper 17 (Th17) axis inflammatory pathway; and iii) the immunopathogenesis of the two conditions is a consequence of the interactions between IL-17 cytokines with effector Th17 cells, T regulatory cells, as well as B cells. In addition, the therapeutic efficacy of IL-17 or TNF-α inhibitors has been demonstrated in PS, and has also become evident in SLE. However, the mechanisms have not been investigated. To the best of our knowledge, there remains a lack of substantial studies on the correlation between PS and SLE. In the present review, the literature, with regards to the epidemiology, genetic predisposition, inflammatory mechanisms and treatment of the patients with both PS and SLE, has been reviewed. Further investigations into the molecular pathogenic mechanism may provide drug targets that could benefit the patients with concomitant PS and SLE.

PTPN22 intron polymorphism rs1310182 (c.2054-852T>C) is associated with type 1 diabetes mellitus in patients of Armenian descent

Protein tyrosine phosphatase, nonreceptor type 22 (PTPN22), is an archetypal non-HLA autoimmunity gene. It is one of the most prominent genetic contributors to type 1 diabetes mellitus outside the HLA region, and prevalence of its risk variants is subject to enormous geographic variability. Here, we address the genetic background of patients with type 1 diabetes mellitus of Armenian descent. Armenia has a population that has been genetically isolated for 3000 years. We hypothesized that two PTPN22 polymorphisms, rs2476601 and rs1310182, are associated with type 1 diabetes mellitus in persons of Armenian descent. In this association study, we genotyped the allelic frequencies of two risk-associated PTPN22 variants in 96 patients with type 1 diabetes mellitus and 100 controls of Armenian descent. We subsequently examined the associations of PTPN22 variants with the manifestation of type 1 diabetes mellitus and its clinical characteristics. We found that the rs2476601 minor allele (c.1858T) frequency in the control population was very low (q = 0.015), and the trend toward increased frequency of c.1858CT heterozygotes among patients with type 1 diabetes mellitus was not significant (OR 3.34, 95% CI 0.88-12.75; χ2 test p > 0.05). The control population had a high frequency of the minor allele of rs1310182 (q = 0.375). The frequency of c.2054-852TC heterozygotes was significantly higher among the patients with type 1 diabetes mellitus (OR 2.39, 95% CI 1.35-4.24; χ2 test p < 0.001), as was the frequency of the T allele (OR 4.82, 95% CI 2.38-9.76; χ2 test p < 0.001). The rs2476601 c.1858CT genotype and the T allele correlated negatively with the insulin dose needed three to six months after diagnosis. The rs1310182 c.2054-852CC genotype was positively associated with higher HbA1c at diagnosis and 12 months after diagnosis. We have provided the first information on diabetes-associated polymorphisms in PTPN22 in a genetically isolated Armenian population. We found only a limited contribution of the prototypic gain-of-function PTPN22 polymorphism rs2476601. In contrast, we found an unexpectedly close association of type 1 diabetes mellitus with rs1310182.

Mutation of Hashimoto’s Thyroiditis and Papillary Thyroid Carcinoma Related Genes and the Screening of Candidate Genes

Clinical studies have shown similarities in the genetic background and biological functional characteristics between Hashimoto’s thyroiditis (HT) and papillary thyroid carcinoma (PTC), and that HT may increase risks of PTC. Here, we set to determine the gene expression specificity of HT and PTC by screening related genes or co-expressed genes and exploring their genetic correlation. Referencing the Oncomine database, HT-related genes were discovered to be expressed in many different types of thyroid cancer, such as TSHR that is highly expressed in thyroid cancer. An in-depth genetic analysis and verification of 35 cancer and paracancerous tissue pairs from patients with thyroid cancer, and 35 tissues and blood cells pairs from patients with Hashimoto’s thyroiditis was conducted. Gene chip technology research showed that TSHR, BACH2, FOXE1, RNASET2, CTLA4, PTPN22, IL2RA and other HT-related genes were all expressed in PTC, in which TSHR was significantly over-expressed in PTC patients sensitive to radioactive iodine therapy, while BACH2 was significantly under-expressed in these patients. The biologically significant candidate Tag SNP highlighted from HT-related genes was screened by the high-throughput detection method. Somatic mutations in patients with HT and PTC were detected by target region capture technique, and 75 mutations were found in patients with HT and PTC. The upstream regulatory factors of the different genes shared by HT and PTC were analyzed based on Ingenuity Pathway Analysis (IPA), and it was found that HIF-1α and PD-L1 could be used as important upstream regulatory signal molecules. These results provide a basis for screening key diagnostic genes of PTC by highlighting the relationship between some HT-related genes and their polymorphisms in the pathogenesis of PTC.

Polymorphisms of the genes CTLA4, PTPN22, CD40, and PPARG and their roles in Graves' disease: susceptibility and clinical features

PURPOSE

CTLA4, PTPN22, and CD40 are immune-regulatory genes strongly associated with GD, as well as PPARG, but their clinical significance in different populations is still uncertain.

METHODS

We genotyped 282 Brazilian GD patients (234 women and 48 men, 39.80 ± 11.69 years old), including 144 patients with GO, and 308 healthy control individuals (246 women and 62 men, 36.86 ± 12.95 years old).

RESULTS

A multivariate analysis demonstrated that the inheritance of the GG genotype rs3087243 of CTLA4 (OR = 2.593; 95% CI = 1.630-4.123; p < 0.0001) and the CC genotype of rs3789607 of PTPN22 (OR = 2.668; 95% CI = 1.399-5.086; p = 0.0029) consisted in factors independent of the susceptibility to GD. The inheritance of polymorphic genotypes of rs5742909 of CTLA4 was associated with older age at the time of diagnosis (42.90 ± 10.83 versus 38.84 ± 11.81 years old; p = 0.0105), with higher TRAb levels (148.17 ± 188.90 U/L versus 112.14 ± 208.54 U/L; p = 0.0229) and the need for higher therapeutic doses of radioiodine (64.23 ± 17.16 versus 50.22 ± 16.86; p = 0.0237). The inheritance of the CC genotype of rs1883832 CD40 gene was more frequent among women (69.65%) than men (52.00%; p = 0.0186). The polymorphic genotype of PPARG gene (rs1801282) was associated with TPOAb positivity (p = 0.0391), and the GG genotype of rs2476601 of PTPN22 gene was associated with positivity for both TgAb (p = 0.0360) and TPOAb (p < 0.0001). Both polymorphic genotypes rs2476601 and rs3789607 of the PTPN22 gene were more frequent among nonsmoking patients (p = 0.0102 and p = 0.0124, respectively).

CONCLUSIONS

Our data confirm the important role of CTLA4 polymorphisms in GD susceptibility; demonstrate the role of PTPN22 polymorphisms in patients' clinical features; and suggest these genes may influence the severity of the disease.

PTPN22 Gene Polymorphisms in Pediatric Systemic Lupus Erythematosus

Objective: Pediatric systemic lupus erythematosus (PSLE) is a heterogeneous autoimmune disorder of unknown origin. PTPN22 gene polymorphisms have been associated with SLE in different populations. We investigated the associations of the rs2476601, rs1217414, rs33996649, rs1276457, and rs1310182 SNPs in the PTPN22 gene with PSLE. Materials and methods: 55 PSLE patients and 93 healthy controls were recruited. SNPs were genotyped by the real-time PCR allelic discrimination method. Results: We found that the PTPN22 polymorphisms rs1310182 A allele (p = 0.01, OR = 1.92 95% CI = 1.16-3.18), and rs1310182 AA genotype with (p < 0.001) and rs12760457 TT (p = 0.046) were associated with PSLE. No significant associations were found between other SNPs and PSLE. Conclusions: The PTPN22 rs1310182 A allele and rs1310182 AA genotype were associated with PSLE and may be a possible genetic marker for susceptibility to PSLE. However, further investigation would be required to elucidate the mechanistic role of this association.

Region 1p13.2 including the RSBN1, PTPN22, AP4B1 and long non-coding RNA genes does not bear risk factors for endemic pemphigus foliaceus (fogo selvagem)

Pemphigus foliaceus (PF) is an autoimmune skin disease characterized by autoantibodies directed mainly against desmoglein-1. The purpose of this study was to determine whether differential susceptibility to endemic PF in Brazil (fogo selvagem) is associated with polymorphisms at the cytogenetic location 1p13.2. Four single nucleotide polymorphisms that together tag 28 SNPs on a segment of approximately 312,000 bp encompassing the protein-coding genes MAGI3, PHTF1, RSBN1, PTPN22, BCL2L15, AP4B1, DCLRE1B, the pseudogenes MTND5P20, RPS2P14 (AL133517.1) and the long non-coding RNA genes AL137856.1, and AP4B1-AS1 were used as markers for association analysis in a case-control study. Allele, genotype and haplotype frequencies of rs33996649, rs2476601, rs3789604 and rs3195954 were compared between patient and control samples. No significant association was found. Lack of association with rs2476601 of the PTPN22 gene agrees with previous results for pemphigus vulgaris and the Tunisian form of endemic pemphigus foliaceus. The other three SNPs had never been analysed before in any form of pemphigus. We conclude that variants in structural and regulatory sites of region 1p13.2 are not susceptibility factors for fogo selvagem. We suggest careful investigation of this genomic region in diseases that had been previously associated with PTPN22, since there are several other genes relevant for immune-mediated diseases located in 1p13.2.

Cannabinoid Signaling in the Skin: Therapeutic Potential of the "C(ut)annabinoid" System

The endocannabinoid system (ECS) has lately been proven to be an important, multifaceted homeostatic regulator, which influences a wide-variety of physiological processes all over the body. Its members, the endocannabinoids (eCBs; e.g., anandamide), the eCB-responsive receptors (e.g., CB₁, CB₂), as well as the complex enzyme and transporter apparatus involved in the metabolism of the ligands were shown to be expressed in several tissues, including the skin. Although the best studied functions over the ECS are related to the central nervous system and to immune processes, experimental efforts over the last two decades have unambiguously confirmed that cutaneous cannabinoid ("c[ut]annabinoid") signaling is deeply involved in the maintenance of skin homeostasis, barrier formation and regeneration, and its dysregulation was implicated to contribute to several highly prevalent diseases and disorders, e.g., atopic dermatitis, psoriasis, scleroderma, acne, hair growth and pigmentation disorders, keratin diseases, various tumors, and itch. The current review aims to give an overview of the available skin-relevant endo- and phytocannabinoid literature with a special emphasis on the putative translational potential, and to highlight promising future research directions as well as existing challenges.

Epigenome-wide DNA methylation regulates cardinal pathological features of psoriasis

Background

Psoriasis is a chronic inflammatory autoimmune skin disorder. Several studies suggested psoriasis to be a complex multifactorial disease, but the exact triggering factor is yet to be determined. Evidences suggest that in addition to genetic factors, epigenetic reprogramming is also involved in psoriasis development. Major histopathological features, like increased proliferation and abnormal differentiation of keratinocytes, and immune cell infiltrations are characteristic marks of psoriatic skin lesions. Following therapy, histopathological features as well as aberrant DNA methylation reversed to normal levels. To understand the role of DNA methylation in regulating these crucial histopathologic features, we investigated the genome-wide DNA methylation profile of psoriasis patients with different histopathological features.

Results

Genome-wide DNA methylation profiling of psoriatic and adjacent normal skin tissues identified several novel differentially methylated regions associated with psoriasis. Differentially methylated CpGs were significantly enriched in several psoriasis susceptibility (PSORS) regions and epigenetically regulated the expression of key pathogenic genes, even with low-CpG promoters. Top differentially methylated genes overlapped with PSORS regions including S100A9, SELENBP1, CARD14, KAZN and PTPN22 showed inverse correlation between methylation and gene expression. We identified differentially methylated genes associated with characteristic histopathological features in psoriasis. Psoriatic skin with Munro’s microabscess, a distinctive feature in psoriasis including parakeratosis and neutrophil accumulation at the stratum corneum, was enriched with differentially methylated genes involved in neutrophil chemotaxis. Rete peg elongation and focal hypergranulosis were also associated with epigenetically regulated genes, supporting the reversible nature of these characteristic features during remission and relapse of the lesions.

Conclusion

Our study, for the first time, indicated the possible involvement of DNA methylation in regulating the cardinal pathophysiological features in psoriasis. Common genes involved in regulation of these pathologies may be used to develop drugs for better clinical management of psoriasis.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0541-9) contains supplementary material, which is available to authorized users.

The Protein Tyrosine Phosphatase Nonreceptor 22 (PTPN22) R620W Functional Polymorphism in Psoriasis

Background:

Psoriasis is a complex autoimmune disease caused by the interaction of genetic and environmental factors. PTPN22 gene polymorphism has been reported to affect psoriasis susceptibility; however, no data are available for Middle Eastern populations.

Objective:

The aim of this study was to investigate the association of PTPN22 (1858C/T) R620W polymorphism with psoriasis in a Saudi cohort.

Methods:

Saudi subjects (n = 306) including patients with psoriasis (n = 106) and matched controls (n = 200) were studied for PTPN22 variants using tetra-primer amplification refractory mutation system-polymerase chain reaction method. The frequencies of alleles and genotypes of PTPN22 (1858C/T) polymorphism were compared between patients and controls.

Results:

The frequency of CT genotype of PTPN22 (1858C/T) polymorphism was significantly higher, whereas that of CC genotype was lower in patients with psoriasis than in controls (P < .001, relative risk [RR] = 7.151). The homozygous genotype TT was absent in both the patients and healthy controls. The frequency of allele T encoding tryptophan (W) was significantly increased (P < .001, RR = 5.76), whereas that of allele C encoding arginine (R) decreased in psoriasis cases as compared with controls (P < .001, RR = 0.173) indicating that individuals carrying allele T are more susceptible to psoriasis than noncarriers.

Conclusions:

PTPN22 (1858C/T) polymorphism is positively associated with susceptibility of psoriasis in Saudis and can be developed as biomarker for evaluating psoriasis risk. However, further studies on PTPN22 polymorphism in larger samples from different geographical areas and ethnicity are warranted.

Association of PTPN22 Single Nucleotide Polymorphisms with Celiac Disease

OBJECTIVES

Celiac disease is a chronic autoimmune disease in which gene-environment interactions cause the immune system to unfavorably react to naturally gluten-containing foods. PTPN22 plays a crucial role in regulating the function of various cells of the immune system, particularly T cells. Polymorphisms of the PTPN22 gene have been associated with many autoimmune diseases. The present genetic association study was conducted to investigate the possible associations between PTPNTT single nucleotide polymorphisms (SNPs) and celiac disease in an Iranian population.

MATERIALS AND METHODS

The study population consisted of 45 patients with celiac disease and 93 healthy controls. The study genotyped five SNPs of the PTPN22 gene: rs12760457, rs1310182, rs1217414, rs33996649, and rs2476601.

RESULTS AND CONCLUSIONS

Control and patient groups did not differ on the genotype distribution of four of five investigated SNPs in the PTPN22 gene, for example, rs12760457, rs2476601, rs1217414, and rs33996649. The only investigated PTPN22 variant, which could be associated with CD, was rs1310182. A significant increase in the carriage of the T allele of rs1310182 in CD patients was observed (OR (95% CI) = 11.42 (5.41, 24.1), p value < 0.0001). The TT genotype of this SNP was significantly associated with celiac disease. Our study suggests that the rs1310182 SNP of PTPN22 gene may be a predisposing factor of celiac disease in the Iranian population. Further studies are required to investigate the issue in other racial and ethnic subgroups.

PTPN22 polymorphisms, but not R620W, were associated with the genetic susceptibility of systemic lupus erythematosus and rheumatoid arthritis in a Chinese Han population

OBJECTIVES

The present study aimed to detect a possible association between PTPN22 gene polymorphisms and rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) in a Chinese Han population.

METHODS

7 PTPN22 SNPs were genotyped in 358 patients with RA and 713 patients with SLE, as well as 564 RA controls and 672 SLE controls by Restriction Fragment Length Polymorphism (RFLP). Association analyses were conducted on the whole data set. Significant relationships were also examined between clinical features and SNPs for both RA and SLE.

RESULTS

Rs2476601 was lack of polymorphism with a ⩽0.1% frequency in both SLE and RA patients and healthy controls in our study. The two SNPs rs1217414 and rs3811021 of PTPN22 shown strong association with both SLE (rs1217414T: padj = 6.07e-004, OR=0.57; rs3811021C: padj = 4.68e-005, OR=0.65) and RA (rs1217414T: padj = 2.01e-008, OR=0.26; rs3811021C: padj = 0.028, OR=0.70). And the rs3765598 revealed a strong risk factor for SLE (p=9.38e-009, padj = 6.57e-008, OR=1.93), but not for RA (p=0.48, OR=1.12). Moreover, protective haplotype ACTTC in RA (p=7.73e-016, padj = 5.51-015, OR[95%CI]=0.02[0.002-0.10]) and SLE (p=8.29e-018, padj = 5.80e-017, OR[95%CI]=0.11[0.06-0.21]) were observed. In addition, the distribution of risk haplotypes ACGTC and GCTTT in RA (ACGTC: p=0.0006, padj = 0.004, OR[95%CI]=1.85[1.29-2.63]; GCTTT: p=2.62e-005, padj = 1.85e-004, OR[95%CI]=2.40[1.57-3.65]) and SLE (ACGTC: p=0.0006, padj = 0.004, OR[95%CI]=1.85[1.29-2.63]; ACGTC: p=7.74e-011, padj = 6.81e-010, OR[95%CI]=2.21[1.12-3.34]; GCTTT: p=2.40[1.57-3.65], padj = 2.26e-006, OR[95%CI]=2.64[1.79-3.87]) were significant different from that in controls. Furthermore, significant association was observed between the PTPN22 rs3765598 and antinuclear antibodies 1 (ANA1) in SLE.

CONCLUSIONS

Our data provide strong evidence that the rs1217414 and rs3811021 in PTPN22 gene might be common protective factors contributed to SLE and RA susceptibility in the Chinese Han population. While, the rs3765598 might increase the genetic susceptibility of SLE, but not RA.

Association between a gain-of-function variant of PTPN22 and rejection in liver transplantation

BACKGROUND

The protein tyrosine phosphatase nonreceptor 22 gene (PTPN22) encodes a strong T-cell regulator called lymphoid protein tyrosine phosphatase. Previously, PTPN22 was described as a susceptibility gene for autoimmunity because it contains single nucleotide polymorphisms (SNPs) associated with several autoimmune diseases. One SNP (rs2476601; 1858G>A) has emerged as a particularly potent risk factor for autoimmunity. We address the question whether PTPN22 polymorphisms are also associated with acute rejection after liver transplantation.

METHODS

We investigated the influence of six PTPN22 SNPs on the susceptibility to acute liver allograft rejection. Consequently, we carried out a retrospective study genotyping 345 German liver recipients at six SNP loci, which include rs2488457 (-1123G>C), rs33996649 (788C>T), rs2476601 (1858G>A), rs1310182 (-852A>G), rs1217388 (-2200G>A), rs3789604 (64434T>G). Our study enrolled 165 recipients who did not develop rejection, 123 who showed one rejection episode, and 57 patients who suffered from multiple acute rejections after transplantation.

RESULTS

The 1858A allele containing genotypes (GA+AA) and the 1858A allele had a significantly higher frequency in the group of patients with multiple rejection episodes (35.1% and 18.4%) compared to rejection-free patients (15.8% and 7.9%; P=0.022 and 0.023). In contrast, we could not detect any association between rejection and the other tested SNPs. Additionally, we identified one haplotype contributing to risk of multiple rejections, however, exhibiting no stronger impact than the 1858A allele alone.

CONCLUSION

We conclude that the 1858G>A SNP may confer susceptibility to multiple acute liver transplant rejections in the German population.

PTPN22 is associated with susceptibility to psoriatic arthritis but not psoriasis: evidence for a further PsA-specific risk locus

Objectives

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with psoriasis; it has a higher estimated genetic component than psoriasis alone, however most genetic susceptibility loci identified for PsA to date are also shared with psoriasis. Here we attempt to validate novel single nucleotide polymorphisms selected from our recent PsA Immunochip study and determine specificity to PsA.

Methods

A total of 15 single nucleotide polymorphisms were selected (P_Immunochip <1×10⁻⁴) for validation genotyping in 1177 cases and 2155 controls using TaqMan. Meta-analysis of Immunochip and validation data sets consisted of 3139 PsA cases and 11 078 controls. Novel PsA susceptibility loci were compared with data from two large psoriasis studies (WTCCC2 and Immunochip) to determine PsA specificity.

Results

We found genome-wide significant association to rs2476601, mapping to PTPN22 (p=1.49×10⁻⁹, OR=1.32), but no evidence for association in the psoriasis cohort (p=0.34) and the effect estimates were significantly different between PsA and psoriasis (p=3.2×10⁻⁴). Additionally, we found genome-wide significant association to the previously reported psoriasis risk loci; NOS2 (rs4795067, p=5.27×10⁻⁹).

Conclusions

For the first time, we report genome-wide significant association of PTPN22 (rs2476601) to PsA susceptibility, but no evidence for association to psoriasis.

Genetic and epigenetic basis of psoriasis pathogenesis

Psoriasis is a chronic inflammatory skin disease whose prevalence varies among different populations worldwide. It is a complex multi-factorial disease and the exact etiology is largely unknown. Family based studies have indicated a genetic predisposition; however they cannot fully explain the disease pathogenesis. In addition to genetic susceptibility, environmental as well as gender and age related factors were also been found to be associated. Recently, imbalances in epigenetic networks are indicated to be causative elements in psoriasis. The present knowledge of epigenetic involvement, mainly the DNA methylation, chromatin modifications and miRNA deregulation is surveyed here. An integrated approach considering genetic and epigenetic anomalies in the light of immunological network may explore the pathogenesis of psoriasis.

Association of PTPN22 polymorphsims and ankylosing spondylitis susceptibility

BACKGROUND

As a susceptibility gene for AS, the polymorphsims of PTPN22 associated with disease susceptibility.

METHODS

We selected two SNPs of rs1217406 and rs1217414 within PTPN22 with Haploview software and investigated the relationship between the SNPs of PTPN22 gene and AS susceptibility. 120 AS patients and 100 healthy people were enrolled from Qilu Hospital of Shandong University. And we genotyped the SNPs of PTPN22 with PCR-RFLP method.

RESULTS

The results showed that C allele (rs1217406) and T allele (rs1217414) both were risk factors for AS (OR: 3.12, 2.13). The persons with A-T, C-C or C-T haplotypes were more likely to suffer AS (OR: 3.17, 3.66, 4.011).

CONCLUSIONS

Due to the close relationship of PTPN22 and AS, the study may be helpful for the early diagnosis and differential diagnosis.

Association analyses identifying two common susceptibility loci shared by psoriasis and systemic lupus erythematosus in the Chinese Han population

BACKGROUND

Genome-wide association studies (GWASs) have revealed a large number of genetic risk loci for many autoimmune diseases. One clear finding emerging from the published genetic studies of autoimmunity is that different autoimmune diseases, such as psoriasis and systemic lupus erythematosus (SLE), share susceptibility loci. Our study explores additional susceptibility loci shared by psoriasis and SLE in the Chinese Han population.

METHODS

In total, 20 single nucleotide polymorphisms (SNPs) in 17 previously reported psoriasis susceptibility loci and 34 SNPs from 24 previously reported SLE susceptibility loci were investigated in our initial psoriasis and SLE GWAS dataset. Among these SNPs, we selected two SNPs (rs8016947 and rs4649203) with association values of p<5×10(-2) for both diseases in the GWAS data for further investigation in psoriasis (7260 cases and 9842 controls) and SLE (2207 cases and 9842 controls) using a Sequenom MassARRAY system.

RESULTS

We found that these two SNPs (rs8016947 and rs4649203) in two loci (NFKBIA and IL28RA) were associated with psoriasis and SLE with genome-wide significance (Pcombined<5×10(-8) in psoriasis and Pcombined<5×10(-8) in SLE): rs8016947 at NFKBIA (Pcombined-psoriasis=3.90×10(-10), Pcombined-SLE=1.08×10(-13)) and rs4649203 at IL28RA (Pcombined-psoriasis=3.91×10(-12), Pcombined-SLE=9.90×10(-9)).

CONCLUSIONS

These results showed that two common susceptibility loci (NFKBIA and IL28RA) are shared by psoriasis and SLE in the Chinese Han population.

PTPN22 association in systemic lupus erythematosus (SLE) with respect to individual ancestry and clinical sub-phenotypes

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is a negative regulator of T-cell activation associated with several autoimmune diseases, including systemic lupus erythematosus (SLE). Missense rs2476601 is associated with SLE in individuals with European ancestry. Since the rs2476601 risk allele frequency differs dramatically across ethnicities, we assessed robustness of PTPN22 association with SLE and its clinical sub-phenotypes across four ethnically diverse populations. Ten SNPs were genotyped in 8220 SLE cases and 7369 controls from in European-Americans (EA), African-Americans (AA), Asians (AS), and Hispanics (HS). We performed imputation-based association followed by conditional analysis to identify independent associations. Significantly associated SNPs were tested for association with SLE clinical sub-phenotypes, including autoantibody profiles. Multiple testing was accounted for by using false discovery rate. We successfully imputed and tested allelic association for 107 SNPs within the PTPN22 region and detected evidence of ethnic-specific associations from EA and HS. In EA, the strongest association was at rs2476601 (P = 4.7 × 10(-9), OR = 1.40 (95% CI = 1.25-1.56)). Independent association with rs1217414 was also observed in EA, and both SNPs are correlated with increased European ancestry. For HS imputed intronic SNP, rs3765598, predicted to be a cis-eQTL, was associated (P = 0.007, OR = 0.79 and 95% CI = 0.67-0.94). No significant associations were observed in AA or AS. Case-only analysis using lupus-related clinical criteria revealed differences between EA SLE patients positive for moderate to high titers of IgG anti-cardiolipin (aCL IgG >20) versus negative aCL IgG at rs2476601 (P = 0.012, OR = 1.65). Association was reinforced when these cases were compared to controls (P = 2.7 × 10(-5), OR = 2.11). Our results validate that rs2476601 is the most significantly associated SNP in individuals with European ancestry. Additionally, rs1217414 and rs3765598 may be associated with SLE. Further studies are required to confirm the involvement of rs2476601 with aCL IgG.

Study of the common genetic background for rheumatoid arthritis and systemic lupus erythematosus

Background

Evidence is beginning to emerge that there may be susceptibility loci for rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) that are common to both diseases.

Objective

To investigate single nucleotide polymorphisms that have been reported to be associated with SLE in a UK cohort of patients with RA and controls.

Methods

3962 patients with RA and 9275 controls were included in the study. Eleven SNPs mapping to confirmed SLE loci were investigated. These mapped to the TNFSF4, BANK1, TNIP1, PTTG1, UHRF1BP1, ATG5, JAZF1, BLK, KIAA1542, ITGAM and UBE2L3 loci. Genotype frequencies were compared between patients with RA and controls using the trend test.

Results

The SNPs mapping to the BLK and UBE2L3 loci showed significant evidence for association with RA. Two other SNPs, mapping to ATG5 and KIAA1542, showed nominal evidence for association with RA (p=0.02 and p=0.02, respectively) but these were not significant after applying a Bonferroni correction. Additionally, a significant global enrichment in carriage of SLE alleles in patients with RA compared with controls (p=9.1×10⁻⁷) was found. Meta-analysis of this and previous studies confirmed the association of the BLK and UBE2L3 gene with RA at genome-wide significance levels (p<5×10⁻⁸). Together, the authors estimate that the SLE and RA overlapping loci, excluding HLA-DRB1 alleles, identified so far explain ∼5.8% of the genetic susceptibility to RA as a whole.

Conclusion

The findings confirm the association of the BLK and UBE2L3 loci with RA, thus adding to the list of loci showing overlap between RA and SLE.

The protein tyrosine phosphatase, non-receptor type 22 R620W polymorphism does not confer susceptibility to psoriasis in the genetic homogeneous population of Crete

Recent whole-genome and candidate-gene association studies in patients with psoriasis (PS) have identified a number of single-nucleotide polymorphisms (SNPs) that predispose to disease with moderate risk. Predisposition to PS is known to be affected by genetic variation in human leukocyte antigen-C as well as other non-human leukocyte antigen genes. We recently reported for the first time as a PS-associated SNP the signal transducer and activator of transcription-4 (STAT4) rs7574865 polymorphism, which is also associated with several autoimmune diseases. The aim of this study was to assess whether the functional R620W polymorphism of protein tyrosine phosphatase, non-receptor type 22 (PTPN22) gene encoding the lymphoid-specific tyrosine phosphatase, which is known to be associated with various autoimmune diseases, also confers increased risk for PS in the genetic homogeneous population of Crete. A case-control study was performed with 173 PS patients consecutively recruited and 348 healthy controls, all of them from the island of Crete. We found that the mutated T allele of the PTPN22 1858T SNP was more common in control individuals than in patients with PS (odds ratio = 0.39, 95% confidence interval = 0.11-1.04, p = 0.09). No considerable difference was observed in terms of sex, age of onset, or clinical presentation of psoriatic arthritis. Our results provide evidence that the PTPN22 1858T allele is not a susceptibility factor for PS in the Cretan population.

Lymphoid tyrosine phosphatase and autoimmunity: human genetics rediscovers tyrosine phosphatases

A relatively large number of protein tyrosine phosphatases (PTPs) are known to regulate signaling through the T cell receptor (TCR). Recent human genetics studies have shown that several of these PTPs are encoded by major autoimmunity genes. Here, we will focus on the lymphoid tyrosine phosphatase (LYP), a critical negative modulator of TCR signaling encoded by the PTPN22 gene. The functional analysis of autoimmune-associated PTPN22 genetic variants suggests that genetic variability of TCR signal transduction contributes to the pathogenesis of autoimmunity in humans.

Genetic susceptibility to psoriasis: an emerging picture

Psoriasis is recognized as a complex disease for which multiple genetic and non-genetic factors influence susceptibility. The major susceptibility locus resides in the MHC class I region and, until relatively recently, evidence for non-MHC loci was inconsistent. Like many common diseases, knowledge of the genetic basis of this condition has been advanced dramatically in recent times with the advent of genome-wide association studies using single nucleotide polymorphisms. Here, we give an overview of current knowledge of genetic risk factors for psoriasis and consider emerging studies that may further add to our understanding of the genetic basis of the disease.

Unraveling the genetics of complex diseases: susceptibility genes for rheumatoid arthritis and psoriasis

Talk of numerous genetic risk factors for rheumatoid arthritis (RA) and psoriasis has been percolating for years, but with the exception of the human leukocyte antigen (HLA) region, none have been definitively identified. Recently the results of multiple, well powered, genetic case-control studies have begun to appear providing convincing statistical evidence for at least ten non-HLA related risk genes or loci (C5/TRAF1, CD40, CTLA4, KIF5A/PIP4K2C, MMEL1/TNFRSF14, PADI4, PRKCQ, PTPN22, STAT4, and TNFAIP3/OLIG3) for RA and six (IL12B, IL13, IL23R, STAT2/IL23A, TNFAIP3, and TNIP1) for psoriasis. These initial, novel findings are beginning to shed light on the molecular pathways pertinent to the individual diseases and highlight the pleiotropic effects of several risk factors as well as the allelic heterogeneity underlying susceptibility to these and other autoimmune diseases.

Further genetic evidence for three psoriasis-risk genes: ADAM33, CDKAL1, and PTPN22

Predisposition to psoriasis is known to be affected by genetic variation in HLA-C, IL12B, and IL23R, and although other psoriasis-associated variants have been identified, incontrovertible statistical evidence for these markers has not yet been obtained. To help resolve this issue, we tested 15 single-nucleotide polymorphisms (SNPs) from 7 putative psoriasis-risk genes in 1,448 psoriasis patients and 1,385 control subjects; 3 SNPs, rs597980 in ADAM33, rs6908425 in CDKAL1 and rs3789604 in PTPN22, were significant with the same risk allele as in prior reports (one-sided P<0.05, false discovery rate<0.15). These three markers were tested in a fourth sample set (599 cases and 299 controls); one marker, rs597980, replicated (one-sided P<0.05) and the other two had odds ratios with the same directionality as in the original sample sets. Mantel-Haenszel meta-analyses of all available case-control data, including those published by other groups, showed that these three markers were highly significant (rs597980: P=0.0057 (2,025 cases and 1,597 controls), rs6908425: P=1.57 x 10(-5) (3,206 cases and 4,529 controls), and rs3789604: P=3.45 x 10(-5) (2,823 cases and 4,066 controls)). These data increase the likelihood that ADAM33, CDKAL1, and PTPN22 are true psoriasis-risk genes.