rs2476601 T allele (R620W) defines high-risk PTPN22 type I diabetes-associated haplotypes with preliminary evidence for an additional protective haplotype. Genes Immun. 2009;10 Suppl 1:S21-S26. [PMID: 19956096 DOI: 10.1038/gene.2009.87]

Newly identified genetic variants associated with idiosyncratic drug-induced liver injury

PURPOSE OF REVIEW

Datasets of well characterized drug or herbal and dietary supplement-associated liver injury has provided a rich resource to identify genetic variants associated with hepatic injury that further supports the role of immune activation in drug-induced liver injury (DILI).

RECENT FINDINGS

Using DNA microarrays, whole genome sequencing, HLA-restricted DNA sequencing with appropriate ethnically matched population controls have identified HLA-specific genetic variants for drugs or botanical compounds with the same HLA variant associated with different agents. In addition to HLAs, two genes involved with immune signaling were also identified: a functional PTPN22 variant associated with increased DILI risk to any agent or clinical presentation and a variant in ERAP2 hepatic gene expression that trims peptide in preparation for presentation in the HLA cleft increased the risk for DILI in amoxicillin-clavulanate DILI when present with known HLA risk alleles.

SUMMARY

Variants in HLA and other genes involved in immune regulations further supports immune system activation in DILI. In the future, identifying these variants before exposure may minimize the risk for DILI events, help with assessment of drug causality for causing DILI and with greater understanding of DILI mechanisms, has important implication for future drug development.

Host Genetics at the Intersection of Autoimmunity and COVID-19: A Potential Key for Heterogeneous COVID-19 Severity

COVID-19 presentation is very heterogeneous across cases, and host factors are at the forefront for the variables affecting the disease manifestation. The immune system has emerged as a key determinant in shaping the outcome of SARS-CoV-2 infection. It is mainly the deleterious unconstrained immune response, rather than the virus itself, which leads to severe cases of COVID-19 and the associated mortality. Genetic susceptibility to dysregulated immune response is highly likely to be among the host factors for adverse disease outcome. Given that such genetic susceptibility has also been observed in autoimmune diseases (ADs), a number of critical questions remain unanswered; whether individuals with ADs have a significantly different risk for COVID-19-related complications compared to the general population, and whether studies on the genetics of ADs can shed some light on the host factors in COVID-19. In this perspective, we discuss the host genetic factors, which have been under investigation in association with COVID-19 severity. We touch upon the intricate link between autoimmunity and COVID-19 pathophysiology. We put forth a number of autoimmune susceptibility genes, which have the potential to be additional host genetic factors for modifying the severity of COVID-19 presentation. In summary, host genetics at the intersection of ADs and COVID-19 may serve as a source for understanding the heterogeneity of COVID-19 severity, and hence, potentially holds a key in achieving effective strategies in risk group identification, as well as effective treatments.

Single-cell expression and Mendelian randomization analyses identify blood genes associated with lifespan and chronic diseases

The human lifespan is a heritable trait, which is intricately linked to the development of disorders. Here, we show that genetic associations for the parental lifespan are enriched in open chromatin of blood cells. By using blood expression quantitative trait loci (eQTL) derived from 31,684 samples, we identified for the lifespan 125 cis- and 559 trans-regulated expressed genes (eGenes) enriched in adaptive and innate responses. Analysis of blood single-cell expression data showed that eGenes were enriched in dendritic cells (DCs) and the modelling of cell ligand-receptor interactions predicted crosstalk between DCs and a cluster of monocytes with a signature of cytotoxicity. In two-sample Mendelian randomization (MR), we identified 16 blood cis-eGenes causally associated with the lifespan. In MR, the majority of cis-eGene-disorder association pairs had concordant effects with the lifespan. The present work underlined that the lifespan is linked with the immune response and identifies eGenes associated with the lifespan and disorders.

PTPN22 1858 C/T Exon Polymorphism is not Associated with Graves' Disease in Kashmiri population

Background

Graves' disease (GD) is a multifactorial autoimmune disease with contribution from both genetic and epigenetic factors in its causation. Association of genetic factors and GD has been extensively studied. Gene "protein tyrosine phosphatase nonreceptor 22" (PTPN22) is an important immunoregulatory gene preventing hyper responsiveness of T cells by negatively regulating their signal transduction. Association of single-nucleotide polymorphism (SNP) 1858 C/T within PTPN22 with some autoimmune diseases has been described.

Methods

We aimed to analyze whether 1858 C/T SNP of PTPN22 gene has any association with GD in Kashmiri population. Polymerase chain reaction-restriction fragment length polymorphism was performed for genotyping 1858 C/T SNP in 135 patients with GD and 150 age- and gender-matched healthy controls.

Results

Among the patients with GD, the frequencies of PTPN22 1858 CC, CT, and TT genotypes were 97.7, 2.2, and 0%, respectively, whereas in healthy controls the frequencies of CC, CT genotypes were 100 and 0%, respectively. No significant association was found between PTPN22 1858 C/T SNP and patients with GD.

Conclusion

GD is not associated with PTPN22 1858 C/T SNP in Kashmiri population. Furthermore, 1858 C/T SNP in PTPN22 gene could be a part of variation in different ethnic populations across the globe.

Genomic and genetic studies of systemic sclerosis: A systematic review

Systemic sclerosis is an autoimmune rheumatic disease characterised by fibrosis, vasculopathy and inflammation. The exact aetiology of SSc remains unknown but evidences show that various genetic factors may be involved. This review aimed to assess HLA alleles/non-HLA polymorphisms, microsatellites and chromosomal abnormalities that have thus far been associated with SSc. PubMed, Embase and Scopus databases were searched up to July 29, 2015 using a combination of search-terms. Articles retrieved were evaluated based on set exclusion and inclusion criteria. A total of 150 publications passed the filters. HLA and non-HLA studies showed that particular alleles in the HLA-DRB1, HLA-DQB1, HLA-DQA1, HLA-DPB1 genes and variants in STAT4, IRF5 and CD247 are frequently associated with SSc. Non-HLA genes analysis was performed using the PANTHER and STRING₁₀ databases. PANTHER classification revealed that inflammation mediated by chemokine and cytokine, interleukin and integrin signalling pathways are among the common extracted pathways associated with SSc. STRING₁₀ analysis showed that NFKB1, CSF3R, STAT4, IFNG, PRL and ILs are the main "hubs" of interaction network of the non-HLA genes associated with SSc. This study gathers data of valid genetic factors associated with SSc and discusses the possible interactions of implicated molecules.

Type 1 diabetes: A predictable disease

Type 1 diabetes (T1D) is an autoimmune disease characterized by loss of insulin producing beta cells and reliance on exogenous insulin for survival. T1D is one of the most common chronic diseases in childhood and the incidence is increasing, especially in children less than 5 years of age. In individuals with a genetic predisposition, an unidentified trigger initiates an abnormal immune response and the development of islet autoantibodies directed against proteins in insulin producing beta cells. There are currently four biochemical islet autoantibodies measured in the serum directed against insulin, glutamic decarboxylase, islet antigen 2, and zinc transporter 8. Development of islet autoantibodies occurs before clinical diagnosis of T1D, making T1D a predictable disease in an individual with 2 or more autoantibodies. Screening for islet autoantibodies is still predominantly done through research studies, but efforts are underway to screen the general population. The benefits of screening for islet autoantibodies include decreasing the incidence of diabetic ketoacidosis that can be life threatening, initiating insulin therapy sooner in the disease process, and evaluating safe and specific therapies in large randomized clinical intervention trials to delay or prevent progression to diabetes onset.

Tyrosine phosphatase PTPN22: multifunctional regulator of immune signaling, development, and disease

Inheritance of a coding variant of the protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene is associated with increased susceptibility to autoimmunity and infection. Efforts to elucidate the mechanisms by which the PTPN22-C1858T variant modulates disease risk revealed that PTPN22 performs a signaling function in multiple biochemical pathways and cell types. Capable of both enzymatic activity and adaptor functions, PTPN22 modulates signaling through antigen and innate immune receptors. PTPN22 plays roles in lymphocyte development and activation, establishment of tolerance, and innate immune cell-mediated host defense and immunoregulation. The disease-associated PTPN22-R620W variant protein is likely involved in multiple stages of the pathogenesis of autoimmunity. Establishment of a tolerant B cell repertoire is disrupted by PTPN22-R620W action during immature B cell selection, and PTPN22-R620W alters mature T cell responsiveness. However, after autoimmune attack has initiated tissue injury, PTPN22-R620W may foster inflammation through modulating the balance of myeloid cell-produced cytokines.

PTPN22 gene polymorphism (C1858T) is associated with susceptibility to type 1 diabetes: a meta-analysis of 19,495 cases and 25,341 controls

The protein tyrosine phosphatase N22 (PTPN22) gene C1858T polymorphism has been reported to be associated with susceptibility to type 1 diabetes (T1D) in relatively small sample sizes. This study aimed at investigating the pooled association by carrying out a meta-analysis on the published studies. The Medline, EBSCO, and BIOSIS databases were searched to identify eligible studies published in English before June 2012. The association was assessed by odds ratio (OR) with 95% confidence intervals (CI). The presence of heterogeneity and publication bias was explored by using meta-regression analysis and Begg's test, respectively. A total of 28 studies were involved in this meta-analysis. Across all populations, significant associations were found between the PTPN22 C1858T polymorphism and susceptibility to T1D under genotypic (TT vs. CC [OR = 3.656, 95% CI: 3.139-4.257], CT vs. CC [OR = 1.968, 95% CI: 1.683-2.300]), recessive (OR = 3.147, 95% CI: 2.704-3.663), and dominant models (OR = 1.957, 95% CI: 1.817-2.108). In ethnicity- and sex-stratified analyses, similar associations were found among Caucasians and within Caucasian male and female strata. The meta-analysis results suggest that the PTPN22 C1858T polymorphism was associated with susceptibility to T1D among the Caucasian population, and males who carried the -1858T allele were more susceptible to T1D than females.

From markers to molecular mechanisms: type 1 diabetes in the post-GWAS era

By the year 2000, a draft of the human genome sequence was completed. Millions of single-nucleotide polymorphisms (SNPs) had been deposited into public databases, and high throughput technologies were under development for SNP genotyping. At that time, it was predicted that large case control association studies would provide far better resolution and power than genome-wide linkage studies. Type 1 diabetes was one of the first phenotypes to be examined by genome-wide association studies (GWAS), and to date over 50 genomic regions have been associated with the disease. In general, the great majority of these loci individually contribute a relatively small degree of risk, and most loci lie outside of coding sequences. The identification of molecular mechanisms from these genomic data therefore remains a significant challenge. Here, we summarize genetic candidate, linkage, and association studies of type 1 diabetes and discuss a potential strategy to identify mechanisms of disease from genomic data.

Improving power of genome-wide association studies with weighted false discovery rate control and prioritized subset analysis

The issue of large-scale testing has caught much attention with the advent of high-throughput technologies. In genomic studies, researchers are often confronted with a large number of tests. To make simultaneous inference for the many tests, the false discovery rate (FDR) control provides a practical balance between the number of true positives and the number of false positives. However, when few hypotheses are truly non-null, controlling the FDR may not provide additional advantages over controlling the family-wise error rate (e.g., the Bonferroni correction). To facilitate discoveries from a study, weighting tests according to prior information is a promising strategy. A 'weighted FDR control' (WEI) and a 'prioritized subset analysis' (PSA) have caught much attention. In this work, we compare the two weighting schemes with systematic simulation studies and demonstrate their use with a genome-wide association study (GWAS) on type 1 diabetes provided by the Wellcome Trust Case Control Consortium. The PSA and the WEI both can increase power when the prior is informative. With accurate and precise prioritization, the PSA can especially create substantial power improvements over the commonly-used whole-genome single-step FDR adjustment (i.e., the traditional un-weighted FDR control). When the prior is uninformative (true disease susceptibility regions are not prioritized), the power loss of the PSA and the WEI is almost negligible. However, a caution is that the overall FDR of the PSA can be slightly inflated if the prioritization is not accurate and precise. Our study highlights the merits of using information from mounting genetic studies, and provides insights to choose an appropriate weighting scheme to FDR control on GWAS.

The past, present, and future of genetic associations in type 1 diabetes

Type 1 diabetes mellitus (T1DM) is an autoimmune disease affecting approximately one in 300 individuals in the United States. The majority of genetic research to date has focused on the heritability that predisposes to islet autoimmunity and T1DM. The evidence so far points to T1DM being a polygenic, common, complex disease with major susceptibility lying in the major histocompatibility complex (MHC) on chromosome 6 with other smaller effects seen in loci outside of the MHC. With recent advances in technology, novel means of exploring the human genome have given way to new information in the development of T1DM. The newest technologies, namely high-throughput polymorphism typing and sequencing, have led to a paradigm shift in studying common diseases such as T1DM. In this review we highlight the advances in genetic associations in T1DM in the last several decades and how they have led to a better understanding of T1DM pathogenesis.

Evidence for PTPN22 R620W polymorphism as the sole common risk variant for rheumatoid arthritis in the 1p13.2 region

OBJECTIVE

The PTPN22 rs2476601 genetic variant has been associated with rheumatoid arthritis (RA) and other autoimmune diseases. Some reports suggest that this single-nucleotide polymorphism (SNP) may not be the only causal variant in the region of PTPN22. Our aim was to identify new independent RA-associated common gene variants in the PTPN22 region.

METHODS

We analyzed Wellcome Trust Case-Control Consortium genome-wide association study data for associations in the 397.2 kb PTPN22 region and selected 9 associated SNP (with p < 5 × 10(-3)) for replication and dependence analysis. The replication cohorts comprised 2857 patients with RA and 2994 controls from Spain, Netherlands, and Norway.

RESULTS

We found that 6 of the 9 selected SNP were associated in the Spanish cohort. Of these, 4 were also associated in the Dutch and Norwegian cohorts, and all 6 were associated with RA in the combined analysis. Conditional analyses showed that none of these associations was independent of rs2476601.

CONCLUSION

The SNP rs2476601 located in the PTPN22 gene is the sole common genetic variant associated with RA in the 1p13.2 region, suggesting that neighbor genes of PTPN22 do not have a major influence in RA.

Replication and further characterization of a Type 1 diabetes-associated locus at the telomeric end of the major histocompatibility complex

BACKGROUND

We recently reported an association between Type 1 diabetes and the telomeric major histocompatibility complex (MHC) single nucleotide polymorphism (SNP) rs1233478. As further families have been analyzed in the Type 1 Diabetes Genetics Consortium (T1DGC), we tested replication of the association and, with more data, analyzed haplotypic associations.

METHODS

An additional 2717 case and 1315 control chromosomes have been analyzed from the T1DGC, with human leukocyte antigen (HLA) typing and data for 2837 SNPs across the MHC region.

RESULTS

We confirmed the association of rs1233478 (new data only: P=2.2E-5, OR=1.4). We also found two additional SNPs nearby that were significantly associated with Type 1 diabetes (new data only rs3131020: P=8.3E-9, OR=0.65; rs1592410: P=2.2E-8, OR=1.5). For studies of Type 1 diabetes in the MHC region, it is critical to account for linkage disequilibrium with the HLA genes. Logistic regression analysis of these new data indicated that the effects of rs3131020 and rs1592410 on Type 1 diabetes risk are independent of HLA alleles (rs3131020: P=2.3E-3, OR=0.73; rs1592410: P=2.1E-3, OR=1.4). Haplotypes of 12 SNPs (including the three highly significant SNPs) stratify diabetes risk (high risk, protective, and neutral), with high-risk haplotypes limited to approximately 20,000 bp in length. The 20,000-bp region is telomeric of the UBD gene and contains LOC729653, a hypothetical gene.

CONCLUSIONS

We believe that polymorphisms of the telomeric MHC locus LOC729653 may confer risk for Type 1 diabetes.

Genetics of type 1 diabetes

BACKGROUND

Type 1 diabetes, a multifactorial disease with a strong genetic component, is caused by the autoimmune destruction of pancreatic β cells. The major susceptibility locus maps to the HLA class II genes at 6p21, although more than 40 non-HLA susceptibility gene markers have been confirmed.

CONTENT

Although HLA class II alleles account for up to 30%-50% of genetic type 1 diabetes risk, multiple non-MHC loci contribute to disease risk with smaller effects. These include the insulin, PTPN22, CTLA4, IL2RA, IFIH1, and other recently discovered loci. Genomewide association studies performed with high-density single-nucleotide-polymorphism genotyping platforms have provided evidence for a number of novel loci, although fine mapping and characterization of these new regions remain to be performed. Children born with the high-risk genotype HLADR3/4-DQ8 comprise almost 50% of children who develop antiislet autoimmunity by the age of 5 years. Genetic risk for type 1 diabetes can be further stratified by selection of children with susceptible genotypes at other diabetes genes, by selection of children with a multiple family history of diabetes, and/or by selection of relatives that are HLA identical to the proband.

SUMMARY

Children with the HLA-risk genotypes DR3/4-DQ8 or DR4/DR4 who have a family history of type 1 diabetes have more than a 1 in 5 risk for developing islet autoantibodies during childhood, and children with the same HLA-risk genotype but no family history have approximately a 1 in 20 risk. Determining extreme genetic risk is a prerequisite for the implementation of primary prevention trials, which are now underway for relatives of individuals with type 1 diabetes.

The PTPN22 locus and rheumatoid arthritis: no evidence for an effect on risk independent of Arg620Trp

Objectives

The Trp⁶²⁰ allotype of PTPN22 confers susceptibility to rheumatoid arthritis (RA) and certain other classical autoimmune diseases. There has been a report of other variants within the PTPN22 locus that alter risk of RA; protective haplotype ‘5’, haplotype group ‘6–10’ and susceptibility haplotype ‘4’, suggesting the possibility of other PTPN22 variants involved in the pathogenesis of RA independent of R620W (rs2476601). Our aim was to further investigate this possibility.

Methods

A total of 4,460 RA cases and 4,481 controls, all European, were analysed. Single nucleotide polymorphisms rs3789607, rs12144309, rs3811021 and rs12566340 were genotyped over New Zealand (NZ) and UK samples. Publically-available Wellcome Trust Case Control Consortium (WTCCC) genotype data were used.

Results

The protective effect of haplotype 5 was confirmed (rs3789607; (OR = 0.91, P = 0.016), and a second protective effect (possibly of haplotype 6) was observed (rs12144309; OR = 0.90, P = 0.021). The previously reported susceptibility effect of haplotype 4 was not replicated; instead a protective effect was observed (rs3811021; OR = 0.85, P = 1.4×10⁻⁵). Haplotypes defined by rs3789607, rs12144309 and rs3811021 coalesced with the major allele of rs12566340 within the adjacent BFK (B-cell lymphoma 2 (BCL2) family kin) gene. We, therefore, tested rs12566340 for association with RA conditional on rs2476601; there was no evidence for an independent effect at rs12566340 (P = 0.76). Similarly, there was no evidence for an independent effect at rs12566340 in type 1 diabetes (P = 0.85).

Conclusions

We have no evidence for a common variant additional to rs2476601 within the PTPN22 locus that influences the risk of RA. Arg620Trp is almost certainly the single common causal variant.

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.

The Type I Diabetes Genetics Consortium 'Rapid Response' family-based candidate gene study: strategy, genes selection, and main outcome

Candidate gene studies have long been the principal method for identification of susceptibility genes for type I diabetes (T1D), resulting in the discovery of HLA, INS, PTPN22, CTLA4, and IL2RA. However, many of the initial studies that relied on this strategy were largely underpowered, because of the limitations in genomic information and genotyping technology, as well as the limited size of available cohorts. The Type I Diabetes Genetic Consortium (T1DGC) has established resources to re-evaluate earlier reported genes associated with T1D, using its collection of 2298 Caucasian affected sib-pair families (with 11 159 individuals). A total of 382 single-nucleotide polymorphisms (SNPs) located in 21 T1D candidate genes were selected for this study and genotyped in duplicate on two platforms, Illumina and Sequenom. The genes were chosen based on published literature as having been either 'confirmed' (replicated) or not (candidates). This study showed several important features of genetic association studies. First, it showed the major impact of small rates of genotyping errors on association statistics. Second, it confirmed associations at INS, PTPN22, IL2RA, IFIH1 (earlier confirmed genes), and CTLA4 (earlier confirmed, with distinct SNPs) loci. Third, it did not find evidence for an association with T1D at SUMO4, despite confirmed association in Asian populations, suggesting the potential for population-specific gene effects. Fourth, at PTPN22, there was evidence for a novel contribution to T1D risk, independent of the replicated effect of the R620W variant. Fifth, among the candidate genes selected for replication, the association of TCF7-P19T with T1D was newly replicated in this study. In summary, this study was able to replicate some genetic effects, reject others, and provide suggestions of association with several of the other candidate genes in stratified analyses (age at onset, HLA status, population of origin). These results have generated additional interesting functional hypotheses that will require further replication in independent cohorts.

Overview of the Type I Diabetes Genetics Consortium

The Type I Diabetes Genetics Consortium (T1DGC) is an international, multicenter research program with two primary goals. The first goal is to identify genomic regions and candidate genes whose variants modify an individual's risk of type I diabetes (T1D) and help explain the clustering of the disease in families. The second goal is to make research data available to the research community and to establish resources that can be used by, and that are fully accessible to, the research community. To facilitate the access to these resources, the T1DGC has developed a Consortium Agreement (http://www.t1dgc.org) that specifies the rights and responsibilities of investigators who participate in Consortium activities. The T1DGC has assembled a resource of affected sib-pair families, parent-child trios, and case-control collections with banks of DNA, serum, plasma, and EBV-transformed cell lines. In addition, both candidate gene and genome-wide (linkage and association) studies have been performed and displayed in T1DBase (http://www.t1dbase.org) for all researchers to use in their own investigations. In this supplement, a subset of the T1DGC collection has been used to investigate earlier published candidate genes for T1D, to confirm the results from a genome-wide association scan for T1D, and to determine associations with candidate genes for other autoimmune diseases or with type II diabetes that may be involved with beta-cell function.

Analysis of 19 genes for association with type I diabetes in the Type I Diabetes Genetics Consortium families

In recent years the pace of discovery of genetic associations with type I diabetes (T1D) has accelerated, with the total number of confirmed loci, including the major histocompatibility complex (MHC) region, reaching 43. However, much of the deciphering of the associations at these, and the established T1D loci, has yet to be performed in sufficient numbers of samples or with sufficient markers. Here, 257 single-nucleotide polymorphisms (SNPs) have been genotyped in 19 candidate genes (INS, PTPN22, IL2RA, CTLA4, IFIH1, SUMO4, VDR, PAX4, OAS1, IRS1, IL4, IL4R, IL13, IL12B, CEACAM21, CAPSL, Q7Z4c4(5Q), FOXP3, EFHB) in 2300 affected sib-pair families and tested for association with T1D as part of the Type I Diabetes Genetics Consortium's candidate gene study. The study had approximately 80% power at alpha=0.002 and a minor allele frequency of 0.2 to detect an effect with a relative risk (RR) of 1.20, which drops to just 40% power for a RR of 1.15. At the INS gene, rs689 (-23 HphI) was the most associated SNP (P=3.8 x 10(-31)), with the estimated RR=0.57 (95% confidence interval, 0.52-0.63). In addition, rs689 was associated with age-at-diagnosis of T1D (P=0.001), with homozygosity for the T1D protective T allele, delaying the onset of T1D by approximately 2 years in these families. At PTPN22, rs2476601 (R620W), in agreement with previous reports, was the most significantly associated SNP (P=6.9 x 10(-17)), with RR=1.55 (1.40-1.72). Evidence for association with T1D was observed for the IFIH1 SNP, rs1990760 (P=7.0 x 10(-4)), with RR=0.88 (0.82-0.95) and the CTLA4 SNP rs1427676 (P=0.0005), with RR=1.14 (1.06-1.23). In contrast, no convincing evidence of association was obtained for SUMO4, VDR, PAX4, OAS1, IRS1, IL4, IL4R, IL13, IL12B, CEACAM21 or CAPSL gene regions (http://www.T1DBase.org).