Absence Of Autoantibodies Research Articles

AUTOANTIBODY LEVELS INFLUENCES THE NUMBER AND PHENOTYPE OF INFILTRATING NEUTROPHILS IN INFLAMED JOINTS OF PATIENTS WITH RHEUMATOID ARTHRITIS

AUTOANTIBODY LEVELS INFLUENCES THE NUMBER AND PHENOTYPE OF INFILTRATING NEUTROPHILS IN INFLAMED JOINTS OF PATIENTS WITH RHEUMATOID ARTHRITIS

Thyroid Storm Presenting With Profound Cholestatic Liver Injury: A Rare Diagnostic Dilemma

Introduction: Thyrotoxicosis from Graves disease can cause multi-organ dysfunction including abnormal liver function tests. Severe cholestatic liver injury directly caused by thyroid storm is rare, and can pose a diagnostic dilemma with etiologies such as congestive heart failure, drug-induced liver injury, concurrent primary biliary cirrhosis (PBC), or autoimmune hepatitis (AIH) being more common. We report an unusual case of thyroid storm-induced profound cholestatic liver injury mimicking PBC and AIH overlap syndrome. A 35-year-old female with an unremarkable past medical history presented to a local hospital with a 2-day history of jaundice and pruritus. Physical examination was significant for thyromegaly and right upper quadrant abdominal tenderness. Liver function tests revealed aspartate aminotransferase (AST) of 1935 unit/L, alanine aminotransferase (ALT) of 982 unit/L, alkaline phosphatase of 484 unit/L, total bilirubin (TB) of 21.6 mg/dL, direct bilirubin (DB) of 16.3 mg/dL, INR of 1.8, and a high gammaglobulin (IgG) level. A liver biopsy showing moderate mixed portal and lobular inflammation, bile duct injury, and focal ductular reaction was interpreted as PBC and AIH overlap syndrome. She was discharged after clinical improvement on prednisone. She presented to our hospital 5 days later with new onset tachycardia of 120 beats per minute, thyroid bruit, diffuse abdominal tenderness, and resting tremor. Laboratory data showed improved but abnormal AST, ALT, and INR, and increased TB of 31.1 mg/dL and DB >20.0 mg/dL. Viral hepatitis serologies, antimitochondrial antibody, anti-liver-kidney microsomal antibody, antinuclear antibody, and anti-smooth muscle antibody were negative. IgG level normalized. Her thyroid stimulating hormone (TSH) was <0.01 mcIU/mL and free thyroxine (FT4) was 5.9 ng/dL. TSH receptor antibodies and thyroid stimulating immunoglobulin were positive, suggestive of thyroid storm secondary to Graves disease. A CT scan of the abdomen and transthoracic echocardiogram were grossly normal. Potassium iodide was promptly started. On hospital day 8, she underwent a thyroidectomy given limited medical options. Three weeks after FT4 normalized, her liver function tests also returned to normal. This case demonstrates that in the absence of autoantibodies, hepatotoxic medication, and congestive heart failure, thyrotoxicosis can be a direct cause of severe cholestatic liver injury. It can also produce inflammatory changes and bile duct injury typical of PBC or AIH overlap syndrome. Special attention should be paid to thyroid abnormalities, since early recognition is of paramount importance and appropriate treatment can reverse the hepatic injury, as seen in our case.

Gene expression profiling in understanding the molecular pathogenesis of and response to canakinumab therapy in traps

TNF receptor-associated periodic syndrome (TRAPS) is an autoinflammatory disease causing unprovoked fevers, myalgia, abdominal pain, rash, headaches, and, in severe cases, AA amyloidosis. It is an autosomal dominant condition resulting from variants in the TNF super family receptor 1A (TNFRSF1A) gene [1]. A hallmark of TRAPS is a huge activation of the inflammatory response in the absence of autoantibodies or antigen-specific T-cells [1]. Canakinumab (CAN) is a high-affinity, fully human, selective, anti-IL-1β monoclonal antibody, developed for the treatment of autoinflammatory diseases [2].

THU0482 Gene Expression Profiling of Whole Blood Samples of TRAPS Patients Shows Insight into the Molecular Pathogenesis of TRAPS and Response to Canakinumab Treatment

BackgroundTNF receptor-associated periodic syndrome (TRAPS) is an autoinflammatory disease causing unprovoked fevers, myalgia, abdominal pain, rash, headaches, and, in severe cases, AA amyloidosis. It is an autosomal dominant condition resulting...

AUTOINFLAMMATORY DISEASES IN CHILDREN(The Lecture from 18th of September 2013, Conference «Topical Problems of Diagnostics and Treatment of Juvenile Rheumatoid Arthritis» (18–20 of September, 2013, St. Petersburg))

Data about clinical signs, diagnostics and treatment of hereditary autoinflammatory syndromes, e.g. cryopyrin-associated periodic syndrome (CAPS), familial Mediterranean fever (FMF), TNF-receptor associated periodic syndrome (TRAPS-syndrome), hyperimmunoglobulinemia D syndrome (HIDS), Pyogenic Sterile Arthritis, Pyoderma Gangrenosum and Acne (PAPA) syndrome, juvenile sarcoidosis (Blau-syndrome) are shown in the article. These diseases are typically genetic disease with autosomal dominant and autosomal recessive type of inheritance. All diseases have common pathogenic features, such as spontaneous activation of innate immunity, maintaining of uncontrolled inflammation, absence of auto-antibodies and antigen-specific T-lymphocytes, over-secretion of interleukin-1 and good response to anti-interleukin-1 treatment. In this article you can see the basis of pathogenesis of the diseases, which determine the choice of treatment modalities and diagnostic algorhythms. Differences between clinical phenotypes of cryopyrin-associated periodic syndrome, such as familial cold urticaria (FCAS), Muckle-Wells syndrome and CINCA / NOMID syndrome are described thoroughly. You can find information about the whole group of periodic fevers and their differentiation. Data about international project «EuroFever» which can facilitate international collaboration in the fields of periodic fever are available.

Humoral Immune Mechanism of Liver Injury in Giant Cell Hepatitis With Autoimmune Hemolytic Anemia

Giant cell hepatitis with autoimmune hemolytic anemia (GCH-AHA) is presumed to be an autoimmune disease, but the mechanism of liver injury is unknown. We proposed that in CGH-AHA, the humoral limb of autoimmunity is the dominant force driving progressive liver injury. We studied 6 cases of GCH-AHA and 6 cases of autoimmune hepatitis (AIH) with early childhood onset (3 type 1 and 3 type 2). Liver biopsies were graded for portal and periportal inflammation and for giant cells. Immunohistochemistry characterized cellular inflammation and complement involvement in injury by showing C5b-9 complex in hepatocytes. Clinical and biochemical features at presentation were generally similar; however, the absence of autoantibodies and the presence of Coombs positivity did distinguish GCH-AHA from early-onset AIH. Liver biopsy pathology in CGH-AHA showed giant cells and little inflammation, whereas AIH showed the opposite. C5b-9 staining showed high-grade complement-mediated pan-lobular hepatocyte injury in all of the cases with GCH-AHA, whereas little C5b-9 was seen in hepatocytes in cases with AIH. Inflammation in GCH-AHA comprised mainly lobular macrophages and neutrophils, whereas portal and periportal T-cell and B-cell inflammation characterized cases with AIH. Most cases with AIH responded to therapy with prednisone and azathioprine, whereas most cases with GCH-AHA responded only to rituximab. Widespread complement-mediated hepatocyte injury and typical C3a and C5a complement-driven liver inflammation along with Coombs-positive hemolytic anemia in GCH-AHA provide convincing evidence that systemic B-cell autoimmunity plays a central pathologic mechanism in the disease. Our findings support B-cell-directed immunotherapy as a first-line treatment of GCH-AHA.

PReS13-SPK-1588: Recurrent fevers

Fevers are common in childhood, usually due to infections. Some children however experience recurrent episodes of seemingly unprovoked fevers. These so-called periodic fever syndromes are rare diseases. Clinically they are characterized by generalized inflammation and different combinations of localized tissue inflammation. Skin and joints are often affected in these patients and the long-standing inflammation can lead to irreversible organ damage due to tissue deposition of inflammatory amyloid proteins. Especially the kidney is vulnerable tot his so-called AA-amyloidosis. The spontaneous sterile inflammation in the absence of autoantibodies places the periodic fever syndromes in the same category as systemic juvenile idiopathic arthritis: the group of autoinflammatory diseases. Often these are genetically determined. Over the past 15 years genetic defects have been identified underlying more than twenty such genetic autoinflammatory diseases. These are disorders like Familial Mediterranean Fever, caused by mutations in the MEFV gene, TNF-receptor associated periodic syndrome (TRAPS), caused by mutations in the TNFRSF1A gene and the Chronic Infantile Neurological Cutaneous Articular (CINCA) syndrome, caused by mutations in the NLRP3 gene. Identification of the responsible genes has led to understanding of the pathophysiology and hence to effective targeted therapy. Interleukin-1 has proved to be the central mediator in many of these disorders. This finding in the congenital autoinflammatory diseases has led to novel therapies in more common disorders like interleukin-1 blockade in systemic Juvenile Idiopathic Arthritis. The rarity of the periodic fever syndromes hampers evidence based therapy. International collaboration in the EUROFEVER network has enabled us to better define the clinical picture of these disorders and to select targets for therapeutic research. However, many children currently defy genetic diagnosis. Next generation genetic sequencing efforts will hopefully identify the cause of inflammation in this group of patients. The functional consequences of autoinflammatory diseases are primarily related to the unpredictable fever episodes. However irreversible sequelae, such as hypertrophic arthropathy, chronic renal failure, impaired vision or hearing do occur. Since these are largely preventable by adequate control of inflammation, effective therapy is essential.

OP0174 Exome sequencing identifies a hypermorphic missense mutation in the PLCG2 gene as the cause of a dominantly inherited autoinflammatory disease with immunodeficiency

BackgroundAutoinflammatory diseases are inherited disorders of the innate immune system caused by aberrant activation of the innate immune cells, primarily neutrophils and macrophages. Genetic studies have led to the identification...

Classification, Diagnosis, and Management of Idiopathic Inflammatory Myopathies

The detection and characterization of a large array of autoantibodies, including at least 8 different antisynthetase, anti-SRP, -200/100 (HMGCR), -Mi-2, -CADM-140 (MDA5), -SAE, -p155, -MJ (NXP-2), and -PMS1, frequently associated with distinct and well-defined clinicopathological features, allowed for significant improvement in the definition and diagnosis of idiopathic inflammatory myopathies (IIM). Classification remains difficult, with lingering divergence between the different specialties involved in IIM care, but several categories clearly stand out, including dermatomyositis (DM), overlap myositis (OM), polymyositis, necrotizing myositis, and sporadic inclusion body myositis (s-IBM). Biopsy and histological analysis remain crucial, particularly in the absence of autoantibodies, to accurately specify the diagnosis and rule out mimics such as muscular dystrophies and metabolic myopathies. Numerous infectious agents (in particular human immunodeficiency virus and human T cell lymphotrophic virus-1) and drugs (statins, tumor necrosis factor inhibitors, and proton pump inhibitors) can cause mimic IIM that must also be excluded. Pharmacological treatment, in addition to glucocorticoids and immunoglobulins, now includes mycophenolate mofetil and rituximab, which proved helpful in resistant cases, particularly rituximab in DM and OM. Exercise, initially seen as potentially deleterious, recently was shown to be efficacious and safe. IIM can thus be reasonably well controlled in most cases, although aggressive disease remains refractory to treatment, including some cases of necrotizing myopathy. Sporadic IBM still seems resistant to all medications tested to date.

Absence of Autoantibodies Against Oral and Vascular-Related Cell Lines in the Sera of Patients with Behcet's Disease

Behcet's disease (BD) is an autoinflammatory disease with unclear pathogenesis. The oral and vascular tissue are the main target organs in BD. The role of humoral immunity in pathogenesis of oral and vascular lesions in BD patients has not been well studied. Therefore, the aim of this study was to investigate the presence of autoantibodies in the sera of BD patients using oral and vascular tissue related cell lines. Proteins from oral (KB, HGF-1) and vascular (HUVEC) related cell lines as well as C2C12 (a muscle myoblast cell line) were extracted as representatives of oral and vascular tissue antigens and the presence of autoantibodies in BD's sera were investigated using high throughput two dimensional electrophoresis (2DE) and immunoblotting techniques. Sera of other autoimmune diseases (RA and SLE) and normal individuals were used as controls. After silver staining of 2DE gels, 2831, 2195, 1732, and 1839 spots were detectable in the proteome map of HUVEC, KB, HGF-1, and C2C12 cell lines, respectively. The majority of spots were in the pH range of 5 - 8 and the molecular weight range of 14 - 66 Kd. The immunoreactivity of BD, RA, SLE, and normal sera were not different with separated proteins of the cell lines. According to our results, it seems that humoral immunity is not significantly involved in BD pathogenesis. Therefore, investigation of the role of cellular immunity, especially TH1 and TH17 cells and their cytokine profiles, in the pathogenesis of BD is recommended for future studies.

A Hypermorphic Missense Mutation in PLCG2, Encoding Phospholipase Cγ2, Causes a Dominantly Inherited Autoinflammatory Disease with Immunodeficiency

Whole-exome sequencing was performed in a family affected by dominantly inherited inflammatory disease characterized by recurrent blistering skin lesions, bronchiolitis, arthralgia, ocular inflammation, enterocolitis, absence of autoantibodies, and mild immunodeficiency. Exome data from three samples, including the affected father and daughter and unaffected mother, were filtered for the exclusion of reported variants, along with benign variants, as determined by PolyPhen-2. A total of eight transcripts were identified as possible candidate genes. We confirmed a variant, c.2120C>A (p.Ser707Tyr), within PLCG2 as the only de novo variant that was present in two affected family members and not present in four unaffected members. PLCG2 encodes phospholipase Cγ2 (PLCγ2), an enzyme with a critical regulatory role in various immune and inflammatory pathways. The p.Ser707Tyr substitution is located in an autoinhibitory SH2 domain that is crucial for PLCγ2 activation. Overexpression of the altered p.Ser707Tyr protein and exvivo experiments using affected individuals' leukocytes showed clearly enhanced PLCγ2 activity, suggesting increased intracellular signaling in the PLCγ2-mediated pathway. Recently, our laboratory identified in individuals with cold-induced urticaria and immune dysregulation PLCG2 exon-skipping mutations resulting in protein products with constitutive phospholipase activity but with reduced intracellular signaling at physiological temperatures. In contrast, the p.Ser707Tyr substitution in PLCγ2 causes a distinct inflammatory phenotype that is not provoked by cold temperatures and that has different end-organ involvement and increased intracellular signaling at physiological temperatures. Our results highlight the utility of exome-sequencing technology in finding causal mutations in nuclear families with dominantly inherited traits otherwise intractable by linkage analysis.

Lighting the fires within: the cell biology of autoinflammatory diseases

Autoinflammatory diseases are characterized by seemingly unprovoked pathological activation of the innate immune system in the absence of autoantibodies or autoreactive T cells. Discovery of the causative mutations underlying several monogenic autoinflammatory diseases has identified key regulators of innate immune responses. Recent studies have highlighted the role of misfolding, oligomerization and abnormal trafficking of pathogenic mutant proteins in triggering autoinflammation, and suggest that more common rheumatic diseases may have an autoinflammatory component. This coincides with recent discoveries of new links between endoplasmic reticulum stress and inflammatory signalling pathways, which support the emerging view that autoinflammatory diseases may be due to pathological dysregulation of stress-sensing pathways that normally function in host defence.

Maturity onset diabetes of the young: clinical characteristics and outcome after kidney and pancreas transplantation in MODY3 and RCAD patients: a single center experience

The diabetes and renal phenotype of patients with maturity-onset diabetes of the young (MODY) on a transplantation waiting list is not known; neither is their outcome after pancreas (PT) and/or kidney transplantation (KT). Between 2002 and 2009, we screened 50 of 150 patients referred for kidney and pancreas transplantation to the Kremlin-Bicêtre center for HNF1B and HNF1A mutations if one or more of the following criteria was present (i) an atypical history of diabetes (ii) diabetes with at least one affected parent or two affected relatives, (iii) an absence of auto-antibodies at diagnosis (iv) a persistent secretion of fasting C peptide (v) a personal or a family history of renal cysts or dysplasia. Their phenotype and their outcome were analyzed. Four HNF1A (MODY3) and eight HNF1B mutations [renal cysts and diabetes (RCAD)] were identified. All MODY3 patients had diabetic nephropathy, but only 50% of RCAD patients. Four patients underwent a kidney and pancreas transplantation and two a kidney transplant alone. After 4.1 ± 1.1 years of follow-up, 83% of patients still have a functioning kidney and 75% a functioning pancreas. PT can be proposed with good results for MODY3 and RCAD patients.

Mortality and its predominant causes in a large cohort of patients with biopsy‐determined inflammatory myositis

There is a paucity of literature on the patterns and predictors of mortality in idiopathic inflammatory myopathies (IIM). To determine the patterns and predictors of mortality in a South Australian cohort of patients with biopsy-proven IIM. The living/deceased status (and for deceased patients the causes of death) of patients with histologically determined IIM was determined from the Births, Deaths and Marriages Registry. Standardised mortality ratios (SMR) were generated compared with the age/gender matched South Australian population. The effect of presence/absence of the components of the Bohan and Peter criteria on risk ratios (RR) for mortality was determined. The effect of comorbidities and autoantibodies on mortality was investigated. The SMR for mortality in IIM was 1.75 and was significantly increased in all disease subgroups, being highest in patients with dermatomyositis (2.40). Dominant causes of death were cardiovascular disease (31%), infections (22%) and malignancy (11%). Risk factors for death were age at time of biopsy (hazard ratio 1.05), ischaemic heart disease (RR 2.97, P < 0.0001), proximal weakness at diagnosis (RR 1.8, P= 0.03), definite diagnosis of IIM per the Bohan and Peter criteria (RR 2.14, P < 0.0001), and the absence of autoantibodies (RR 1.9, P < 0.001). Patients with IIM are at 75% increased risk for mortality, and cardiovascular diseases account for the commonest causes of death. This study suggests a thorough cardiovascular evaluation of these patients is indicated, and raises the possibility that targeted interventions such as the use of aspirin or statins may improve outcomes in IIM.

Clinical care of children with sterile bone inflammation

To review the current literature of sterile bone inflammation in childhood and to evaluate the evidence for clinical care including diagnostic methods and treatment. Chronic noninfectious osteomyelitis includes several different entities marked by sterile bone inflammation associated with histologic evidence of a predominant neutrophil infiltration in the absence of autoantibodies and autoreactive T cells, some of which are associated with a genetic mutation. Whole body MRI is helpful in detecting asymptomatic lesions. Initial treatment with NSAIDs is usually sufficient to control symptoms as the bone heals. However, if the lesions persist and do not respond to first-line treatment, or involve the spine or hip, treatment with bisphosphonate will usually lead to a resolution of symptoms. Rarely, treatment with anti-TNF agents is required. This review summarizes recent information on diagnosis, treatment and prognosis of disorders involving sterile bone inflammation in childhood. It also addresses the evolving differential diagnosis for autoinflammatory disorders that include sterile bone inflammation and presents a treatment algorithm for management.

Nucleosomes and C1q bound to glomerular endothelial cells serve as targets for autoantibodies and determine complement activation

Various studies indicate a role for both anti-nucleosome and anti-C1q autoantibodies in glomerulonephritis in patients with systemic lupus erythematosus. However, a causal relationship between these autoantibodies and the development of lupus nephritis has not been fully established. Since injury of the endothelium is a major target in lupus nephritis we assessed the interaction of C1q and nucleosomes with glomerular endothelial cells in vitro in the presence or absence of autoantibodies against these antigens. We demonstrate a direct and dose-dependent binding of both nucleosomes and C1q to immortalized human glomerular endothelial cells (GEnC) in vitro, which in part is mediated by cell surface heparan sulfate. We demonstrate that nucleosomes and C1q serve as targets for monoclonal and polyclonal antibodies as well as for anti-nuclear autoantibodies from patients with systemic lupus erythematosus. An additive effect of anti-C1q autoantibodies on anti-nucleosome mediated complement activation was observed. Furthermore, we showed that the activation of complement on glomerular endothelial cells is mediated by the classical pathway since the deposition of C3 on GEnC is abrogated by MgEGTA and does not occur in C1q-depleted serum. Taken together, our studies demonstrate a direct binding of both nucleosomes and C1q to glomerular endothelial cells in vitro. The subsequent binding of autoantibodies against nucleosomes in patients with systemic lupus erythematosus is potentially pathogenic and autoantibodies against C1q seem to have an additional effect.

A case of IgG4-related disease with features of Mikulicz’s disease, and retroperitoneal fibrosis and lymphadenopathy mimicking Castleman’s disease

A 51-year-old man developed painless enlargement of the bilateral submandibular and lacrimal glands without xerostomia or xerophthalmia in the absence of autoantibodies to SS-A (Ro) and SS-B (La). In a few years, he developed generalized lymphadenopathy, with markedly elevated serum IgG4, and a computed tomography scan revealed soft-tissue-density lesions around the abdominal aorta, a finding consistent with retroperitoneal fibrosis. Biopsy of the cervical lymph node showed an expansion of the interfollicular area by heavily infiltrating plasma cells, consistent with multicentric Castleman's disease. Immunohistochemical analysis revealed that the IgG4-positive/IgG-positive plasma cell ratio was 80%, leading us to a single diagnosis of IgG4-related disease. High-dose corticosteroid treatment resulted in prompt resolution of the physical, serological, and imaging abnormalities. Although IgG4-related disease can mimic multicentric Castleman's disease, as in our patient, the two diseases have effective but distinct treatments, and thus measurement of serum IgG4 levels and specific immunohistochemical analysis for determining the IgG4-positive/IgG-positive plasma cell ratio are recommended if IgG4-related disease is suspected.

Pathogenesis and clinical manifestations of juvenile rheumatoid arthritis.

Juvenile rheumatoid arthritis (JRA) is the most common rheumatic childhood disease; its onset is before 16 years of age and it persists for at least 6 weeks. JRA encompasses a heterogeneous group of diseases that is classified according to 3 major presentations: oligoarthritis, polyarthritis, and systemic onset diseases. These presentations may originate from the same or different causes that involve interaction with specific immunogenetic predispositions, and result in heterogeneous clinical manifestations. An arthritic joint exhibits cardinal signs of joint inflammation, such as swelling, pain, heat, and loss of function; any joint can be arthritic, but large joints are more frequently affected. Extra-articular manifestations include high fever, skin rash, serositis, and uveitis. The first 2 types of JRA are regarded as T helper 1 (Th1) cell-mediated inflammatory disorders, mainly based on the abundance of activated Th1 cells in the inflamed synovium and the pathogenetic role of proinflammatory cytokines that are mainly produced by Th1 cell-stimulated monocytes. In contrast, the pathogenesis of systemic onset disease differs from that of other types of JRA in several respects, including the lack of association with human leukocyte antigen type and the absence of autoantibodies or autoreactive T cells. Although the precise mechanism that leads to JRA remains unclear, proinflammatory cytokines are thought to be responsible for at least part of the clinical symptoms in all JRA types. The effectiveness of biologic therapy in blocking the action of these cytokines in JRA patients provides strong evidence that they play a fundamental role in JRA inflammation.

Frequencies of killer immunoglobulin-like receptor genotypes influence susceptibility to spontaneous abortion

Natural killer (NK) cells are the most abundant lymphocyte population in the decidua. These cells express killer immunoglobulin-like receptors (KIRs), which upon recognition of HLA class I molecules on trophoblasts may either stimulate NK cells (activating KIRs) or inhibit them (inhibitory KIRs) to produce soluble factors necessary for the maintenance of pregnancy. KIR genes exhibit extensive haplotype polymorphism; individuals differ in both the number and kind (activating vs. inhibitory) of KIR genes. This polymorphism affects NK cell reactivity and susceptibility to diseases, including gynecological disorders. Therefore we KIR-genotyped 149 spontaneously aborting women and 117 control multiparae (at least 2 healthy-born children). Several genotypes (i.e. combinations of various KIR genes) were differently distributed among the patients and control subjects. Differences were observed in the numbers and the ratios of activating to inhibitory KIRs between patients and healthy women: (i) genotypes containing 6 activating KIR genes were less frequent and those containing 6 inhibitory KIR genes were more frequent in patients than in control subjects, and (ii) an excess of inhibitory KIRs (activating-to-inhibitory KIR gene ratios of 0.33 to 0.83) was associated with miscarriage, whereas ratios close to equilibrium (0.86-1.25) seemed to be protective. In addition, the results suggest for the first time that sporadic and recurrent spontaneous abortions as well as miscarriage in the presence or absence of autoantibodies may have different KIR genotypic backgrounds.

Rheumatoid arthritis genetics: 2009 update

Recent human genetic discoveries have increased our understanding of rheumatoid arthritis (RA) susceptibility. Genome-wide association studies have expanded the number of validated RA risk loci beyond HLA-DRB1 "shared epitope" alleles to include additional major histocompatibility complex (MHC) risk alleles and more than 10 regions outside the MHC. The newly discovered risk alleles are common in the general population, have a modest effect on RA risk, and together explain less than 5% of the variance in disease risk. Whereas the actual causal mutation and causal gene for most loci remain to be determined, these studies are beginning to reveal general themes: many risk loci are associated with other autoimmune diseases; many genes fall within discrete biological pathways (eg, the nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway); and human genetics can group diseases into clinically meaningful subset categories (eg, presence or absence of autoantibodies). This review discusses recent RA genetic discoveries in terms of their potential to improve patient care.