Implications of combined NOD2 and other gene mutations in autoinflammatory diseases

Ultrarare Variants in DNA Damage Repair Genes in Pediatric Acute-Onset Neuropsychiatric Syndrome or Acute Behavioral Regression in Neurodevelopmental Disorders

INTRODUCTION

Acute onset of severe psychiatric symptoms or regression may occur in children with premorbid neurodevelopmental disorders, although typically developing children can also be affected. Infections or other stressors are likely triggers. The underlying causes are unclear, but a current hypothesis suggests the convergence of genes that influence neuronal and immunological function. We previously identified 11 genes in pediatric acute-onset neuropsychiatric syndrome (PANS), in which two classes of genes related to either synaptic function or the immune system were found. Among the latter, three affect the DNA damage response (DDR): PPM1D, CHK2, and RAG1. We now report an additional 17 cases with mutations in PPM1D and other DDR genes in patients with acute onset of psychiatric symptoms and/or regression that their clinicians classified as PANS or another inflammatory brain condition.

METHODS

We analyzed genetic findings obtained from parents and carried out whole-exome sequencing on a total of 17 cases, which included 3 sibling pairs and a family with 4 affected children.

RESULTS

The DDR genes include clusters affecting p53 DNA repair (PPM1D, ATM, ATR, 53BP1, and RMRP), and the Fanconi Anemia Complex (FANCE, SLX4/FANCP, FANCA, FANCI, and FANCC). We hypothesize that defects in DNA repair genes, in the context of infection or other stressors, could contribute to decompensated states through an increase in genomic instability with a concomitant accumulation of cytosolic DNA in immune cells triggering DNA sensors, such as cGAS-STING and AIM2 inflammasomes, as well as central deficits on neuroplasticity. In addition, increased senescence and defective apoptosis affecting immunological responses could be playing a role.

CONCLUSION

These compelling preliminary findings motivate further genetic and functional characterization as the downstream impact of DDR deficits may point to novel treatment strategies.

TNFRSF11A variants contribute to systemic autoinflammatory diseases: A case series of 12 patients

BACKGROUND

Limited evidence suggests that variants in TNFRSF11A gene, encoding RANK, may contribute to systemic autoinflammatory disease (SAID).

AIM/METHODS

To estimate the prevalence of TNFRSF11A variants in a cohort of patients with SAIDs screened for 26 related genes and describe the disease phenotypic expression.

RESULTS

A total of 12 out of 167 patients, 7 males, aged (median) 38 years at disease onset, yielded at least one TNFRSF11A rare variant. All patients carried a coexisting variant in at least one other SAID-related gene, most frequently MEFV (6 patients), but also TNFRSF1A, NOD2, NLRP3, NLRP7, MVK, IL36RN, RBCK1, PLCG2 and PSMB8. SAID episodes lasting (median) 9 days manifested with high grade fever (91%), myalgias (75%), malaise (67%), serositis (58%), arthralgias/arthritis (58%), gastrointestinal involvement (33%), and rash (25%), and responded to corticosteroids. The most common initial clinical diagnosis was TNF-associated periodic fever syndrome (TRAPS), which was, however, confirmed, in only one patient. The emergence of MEFV variations supported the diagnosis of atypical Familial Mediterranean Fever in two cases, whereas the diagnosis of Yao syndrome was speculated in two patients with NOD2 variants. The presence of atypical disease and the inability of defining diagnosis in the remaining 7 patients, supported the possible involvement of TNFRSF11A variants in the phenotypic expression of SAIDs.

CONCLUSION

TNFRSF11A variants, occurring in 7% of SAID patients always in combination with other SAID-related gene variants, contribute to the development of an autoinflammatory syndrome resembling to TRAPS. Additional studies to confirm novel pathogenic SAID pathways are clearly warranted.

Comprehensive clinical phenotype, genotype and therapy in Yao syndrome

Objective

Yao syndrome (YAOS) is formerly called nucleotide-binding oligomerization domain containing 2 (NOD2)-associated autoinflammatory disease.We report a large cohort of YAOS.

Methods

We conducted a retrospective analysis of a cohort of adult patients with systemic autoinflammatory diseases (SAIDs). All patients underwent testing for a periodic fever syndrome gene panel.

Results

A total of 194 patients carried NOD2 variants, 152 patients were diagnosed with YAOS, and 42 had mixed autoinflammatory diseases with combined variants in NOD2 and other SAID-associated genes. Demographic, clinical and molecular data were summaried. In sub-group analysis of the 194 patients, individual patients were often identified to carry two or more variants that usually included IVS8 + 158/R702W, IVS8 + 158/L1007fs, IVS8 + 158/V955I, IVS8 + 158/other, or NOD2/variants in other SAID genes. Ninety-nine patients carried single variants. Taken together, these variants contribute to the disease in combination or individually.

Conclusion

This largest cohort has provided comprehensive clinical and genotyping data in YAOS. Variants in the NOD2 gene can give rise to a spectrum from inflammatory bowel disease to autoinflammatory disease.This report further raises awareness of the underdiagnosed disease in the medical community.

Yao Syndrome: An Overview of Genotypic Associations, Clinical Manifestations, Diagnosis, and Treatment

BACKGROUND

Yao syndrome (YAOS) is a rare systemic autoinflammatory disorder (AID) of the innate immune system. It was recently categorized as genetically transitional disease (GTD) and is associated with NOD2 variants located at multiple NOD2 gene loci. Unlike most other periodic fever syndromes, the estimated disease prevalence is 1-10/100,000 with a predominance for females and white adult population. In this review, we aimed to provide a detailed analysis of different aspects of this syndrome to help better understand the underlying pathogenesis and incorporate the current evidence-based medicine published to diagnose and manage these patients.

SUMMARY

We conducted literature search on YAOS from 2011 to 2024 using PubMed, Embase, and Scopus databases. Thirty-two studies were included in our narrative review. A descriptive analysis was performed of both Yao and non-Yao authored records to embrace the syndrome reported from all investigators and assess differences and similarities. The most reported gene variant is the homozygous IVS8+158 followed by compound heterozygous IVS8+158 and R702W. Mean age of disease onset is between 36 and 42 years. The mean age of disease diagnosis is between 40 and 45 years with a variable disease duration. Fever is the most commonly reported symptom followed by musculoskeletal, gastrointestinal symptoms and dermatitis. On laboratory workup, patients have elevated levels of erythrocyte sedimentation rate, C-reactive protein, and serum ferritin with negative autoantibody workup. Arthritic symptoms in YAOS patients have a positive response to sulfasalazine and glucocorticoids, while nonsteroidal anti-inflammatory drugs and colchicine produce minimal response. Anti-IL1 and anti-IL6 agents (canakinumab, anakinra, and tocilizumab) are effective treatment modalities.

KEY MESSAGES

The evolving concept and acceptance of GTD will hopefully further our understanding about this SAID and similar disorders. We suggest developing a registry of patients with YAOS to keep track of expanding data on this subject. It is important to understand various aspects of YAOS including genetic and environmental factors, differential diagnosis, clinical manifestations, laboratory findings, and treatment options available to diagnose and manage these patients appropriately and timely.

Expanding clinical characteristics and genotypic profiling of Yao syndrome in Chinese patients

Objectives

Yao syndrome (YAOS, OMIM# 617321) is a kind of systemic autoinflammatory diseases (SAIDs) linked to the nucleotide-binding oligomerization domain containing 2 (NOD2). Clinical reports of YAOS in China are sparse. Herein, we reported the largest YAOS cohort of Chinese patients to expand the understanding of its phenotype, genotype, and therapeutic responses.

Methods

This study enrolled 15 adult patients diagnosed with YAOS at Peking Union Medical College Hospital from April 2015 to May 2024. Whole-exome sequencing was performed on all patients. Clinical data, genetic variations, and treatment responses were documented and compared with a Caucasian cohort.

Results

The mean age of disease onset was 35 ± 17 years old. The most common clinical manifestations included recurrent high-grade fever (100%), gastrointestinal symptoms (73.3%), arthralgia/arthritis, fatigue, myalgia, and lower extremity swelling (46.7%). All patients exhibited elevated acute-phase reactants during episodes. 12 heterozygous NOD2 variants were identified, with Q902K in 4 patients, R471C in 3, and variants c.-14C>T, A110T, S127L, R311W, A432V, Y514H, R541P, A661P, K818Q, A886V each found in individual patients. 90% of the patients responded well to glucocorticoids, and 55.6% to sulfasalazine. 66.7% of patients who received TNF inhibitors achieved complete resolution of symptoms. Additionally, one patient each responded favorably to canakinumab and tocilizumab. Compared to the Caucasian cohort, our cohort exhibited a more balanced gender ratio and a higher proportion of recurrent fever, proteinuria/hematuria as well as more frequent leukocytosis, elevated acute phase reactants, and anemia. Lower proportions of arthralgia/arthritis, skin rashes, headaches, and sicca-like symptoms were noted in our cohort. Moreover, a higher proportion of patients in our cohort showed a good response to TNF inhibitors.

Conclusion

Chinese patients with YAOS had more pronounced inflammatory manifestations compared to the Caucasian cohort. Variants c.-14C>T, A110T, S127L, A661P, K818Q, A886V, R471C, and A432V were identified as novel NOD2 variants in YAOS. TNF, IL-6, and IL-1 inhibitors are the promising treatment options. These findings expand the clinical spectrum, genetic profile, and treatment efficacy of YAOS, underscoring the need for heightened awareness of this disease in diverse populations.

Autoinflammatory Diseases: A Review

Autoinflammatory disease (AID) is a vast spectrum of disorders characterized by recurrent attacks of sterile inflammation. Since the first cloning of the familial Mediterranean fever gene in 1997, there has been a rapid rate of discovery of new AIDs. As of 2022, there have been 485 inborn errors of immunity documented by the International Union of Immunological Societies, for which many display aspects of autoinflammation. The pathophysiology of AIDs is complex. Although many are caused by rare mutations in genes that govern innate immunity, others are polygenic, where disease expression is thought to be triggered by environmental factors in genetically predisposed hosts. AIDs range in prevalence from common entities like gout to ultrarare monogenic diseases. Whereas AIDs were initially studied in pediatric populations, it is now apparent that they can present in adulthood and even in the elderly. AIDs can be clinically challenging given their rarity, as well as the heterogeneity in presentation and underlying etiology. Although the care of AIDs can span medical disciplines, the rheumatologist often plays a central role given the inflammatory nature of these illnesses. In this review, we explore the current understanding of the pathophysiology of these complex conditions and propose a classification system for AIDs. We place an emphasis on AIDs that present to the adult rheumatologist and discuss important AIDs that can mimic more classic rheumatic diseases such as systemic lupus erythematosus and inflammatory arthritis. Finally, we offer an approach to the clinical assessment, diagnosis, and management of AIDs.

Genetic Approaches to Study Rheumatic Diseases and Its Implications in Clinical Practice

Patients with rare and complex rheumatic diseases (RDs) present with immense clinical variability inherent to all immunologic diseases. In addition to systemic and organ-specific inflammation, patients may display features of immunodeficiency or allergy, which may represent major diagnostic and therapeutic challenges. The person's genetic architecture has been a well-established risk factor for patients with RDs, albeit to variable degrees. Patients with early-onset diseases and/or positive family history (FH) have a strong genetic component, whereas patients with late-onset RDs demonstrate a more complex interplay of genetic and environmental risk factors. Overall, the genetic studies in patients with RDs have been instrumental to our understanding of innate and adaptive immunity in human health and disease. The elucidation of the molecular causes underlying rare diseases has played a major role in the identification of genes that are critical in the regulation of inflammatory responses. In addition, studies of patients with rare disorders may help determine the mechanisms of more complex autoimmune diseases by identifying variants with small effect sizes in the same genes. In contrast, studies of patients with common RDs are conducted in cohorts of patients with well-established phenotypes and ancestry-matched controls, and they aim to discover disease-related pathways that can inform the development of novel targeted therapies. Knowing the genetic cause of a disease has helped patients and families understand the disease progression and outcome. Here, we discuss the current understanding of genetic heritability and challenges in the diagnosis of RDs in patients and how this field may develop in the future.

The expanding clinical spectrum of autoinflammatory diseases with NOD2 variants: a case series and literature review

Objective

To assess the impact conferred by NOD2 variants on the clinical spectrum of patients with systemic autoinflammatory diseases (SAIDs) in Greece.

Methods

Consecutive patients (n=167) with confirmed SAIDs who underwent screening by next generation sequencing (NGS) targeting 26 SAID-associated genes, and carried at least one NOD2 gene variant, were retrospectively studied. The demographic, clinical and laboratory parameters were recorded.

Results

In total, 24 rare NOD2 variants in 23/167 patients (14%) were detected. Notably, 18 patients had at least one co-existing variant in 13 genes other than NOD2. Nine patients had juvenile- and 14 adult-onset disease. All patients presented with symptoms potentially induced by the NOD2 variants. In particular, the candidate clinical diagnosis was Yao syndrome (YAOS) in 12 patients (7% of the whole SAID cohort). The clinical spectrum of patients with YAOS (mean episode duration 8 days) was fever (n=12/12), articular symptoms (n=8), gastrointestinal symptoms (n=7; abdominal pain/bloating in 7; diarrhea in 4; oral ulcers in 3), serositis (n=7), and rash (n=5), while the inflammatory markers were elevated in all but one patient. Most of these patients showed a poor response to nonsteroidal anti-inflammatory drugs (n=7/9), colchicine (n=6/8) and/or anti-TNF treatment (n=3/4), while a complete response was observed in 6/10 patients receiving steroids and 3/5 on anti-IL1 treatment. Another 8 patients were diagnosed with either FMF (n=6) or PFAPA syndrome (n=2) presenting with prominent diarrhea (n=7), oral ulcers (n=2), periorbital swelling and sicca-like symptoms (n=1), or maculopapular rash (n=1). One patient had a clinically undefined SAID, albeit characterized by oral ulcers and diarrhea. Finally, one patient presented with chronic relapsing urticaria with periorbital edema and inflammatory markers, and another one had a Crohn-like syndrome with good response to anti-IL-1 but refractory to anti-TNF treatment.

Conclusion

NOD2 variants were detected in 1 out of 7 SAID patients and seem to have an impact on disease phenotype and treatment response. Further studies should validate combined molecular and clinical data to better understand these distinct nosological entities.

Genetic variations in NLRP3 and NLRP12 genes in adult-onset patients with autoinflammatory diseases: a comparative study

Objectives

Cryopyrin-associated periodic syndrome or NLRP3-associated autoinflammatory disease (NLRP3-AID) and NLRP12-AID are both Mendelian disorders with autosomal dominant inheritance. Both diseases are rare, primarily reported in the pediatric population, and are thought to be phenotypically indistinguishable. We provide the largest cohort of adult-onset patients and compared these diseases and the gene variant frequency to population controls.

Methods

A cohort of adult patients with AIDs were retrospectively studied. All underwent molecular testing for periodic fever syndrome gene panels after extensive and negative workups for systemic autoimmune and other related diseases. Patients were divided into Group 1- NLRP3-AID patients with NLRP3 variants (N=15), Group 2- NLRP12-AID with NLRP12 variants (N=14) and Group 3- both NLRP3 and NLRP12 (N=9) variants. Exome sequence data of two large control populations including the ARIC study were used to compare gene variant distribution and frequency.

Results

All 38 patients were Caucasian with women accounting for 82%. Median age at diagnosis was 41 ± 23 years and the disease duration at diagnosis was 14 ± 13 years. We identified statistically significant differences between the groups, notably that gastrointestinal symptoms as well as evaluations for same were significantly more frequent in patients with NLRP12 variants, and headaches/dizziness were less common among the NLRP12 patients. Livedo reticularis was noted in four patients, exclusively among NLRP12 carriers. Over 50% of patients in Groups 1 and 2 carry low-frequency disease-associated variants, while the remaining carry rare variants. We unprecedently identified digenic variants, i.e., the coexistence of NLRP3 and NLRP12, which were either both low frequency or low frequency/rare. Allele frequencies of all variants identified in our cohort were either absent or significantly lower in the control populations, further strengthening the evidence of susceptibility of these variants to SAID phenotypes.

Conclusion

Our comparative study shows that both NLRP3-AID and NLRP12-AID share similar clinical phenotypes, yet there are significant differences between them with regard to gastrointestinal and neurological symptoms. A spectrum of high to low genetic variations in both genes can contribute to SAID individually or in combination.