Novel Deleterious Sequence Change in the NLRP12 Gene in a Child with the Autoinflammatory Syndrome, Joint Hypermobility and Cutis Laxa from India

NLRP12-associated autoinflammatory disease: A novel causal mutation and bioinformatics analyses

Nucleotide-binding leucine-rich repeat-containing receptor 12-associated autoinflammatory disease (NLRP12-AID) is a rare autosomal dominant disorder. In this study, we reported a case of this rare disease with a novel NLRP12 mutation (A218V, rs749659859). The patient displayed typical symptoms, including recurrent fever, arthralgia, and skin allergies. Elevated serum IgE, decreased apolipoprotein A1, high-density lipoprotein cholesterol, and fluctuating levels of various leukocyte subtypes, procalcitonin, IL6, creatine kinase, and 25-hydroxyvitamin D were also detected. Inflammatory lesions were observed in multiple organs using 18F-FDG PET/CT. By mining single-cell transcriptome data, we identified relatively high expression of NLRP12 in monocytes compared to other human peripheral blood mononuclear cells. NLRP12-positive monocytes exhibited reduced expression of IL18, CCL3, and TNFA compared to NLRP12-negative monocytes. Structural analyses suggested that the A218V mutation, along with A218T and F402L, may reduce the ATP-binding affinity of the NLRP12 protein. These findings may provide new insights into the mechanisms of NLRP12-AID, and suggest the potential ATP-based therapy for further investigation.

NLRP12-associated autoinflammatory disease in Chinese adult patients: a single-centre study

BACKGROUND

NLRP12-associated autoinflammatory disease (NLRP12-AID) is an autosomal dominant autoinflammatory disorder caused by variants of NLRP12 gene. We aimed to report a cohort of Chinese adult patients with NLRP12-AID and summarised phenotypes and genotypes.

METHODS

Twenty patients were diagnosed with NLRP12-AID after performing whole-exome sequencing and were included in our cohort. Demographic information, clinical data and treatment response were collected and evaluated. A literature review of NLRP12-AID was performed, and the clinical features and mutated sites were summarised and compared with our cohort.

RESULTS

Among the 20 NLRP12-AID patients, the main clinical features of NLRP12-AID included fever, cutaneous rash, arthralgia/arthritis, pharyngitis/tonsillitis, lymphadenopathy, myalgia and abdominal pain/diarrhoea. Thirteen NLRP12 variants were detected as F402L, G39V, R1030X, R7G, E24A, Q90X, A218V, A259V, W581X, G729R, R859W, c.-150T>C and c.*126G>C. Glucocorticoids were used in 14 patients, immunosuppressive agents in 13, and tocilizumab in 2. Seventeen patients had good responses to therapy. When compared with 50 NLRP12-AID patients from other countries, Chinese patients had fewer variants in exon 3, higher incidences of cutaneous rash, pharyngitis/tonsillitis and lymphadenopathy. Among all these 70 NLRP12-AID patients, patients carrying non-exon-3 variants had higher frequencies of ocular involvement, pharyngitis/tonsillitis, headache and lymphadenopathy than those with exon-3 variants.

CONCLUSION

This is the largest cohort of NLRP12-AID in the world and seven novel variants of NLRP12 were identified. Chinese adult patients of NLRP12-AID had more non-specific symptoms such as pharyngitis/tonsillitis and lymphadenopathy when compared with patients from other countries, for which the less occurrence of exon-3 variants might be one possible reason.

Autoinflammatory Recurrent Pericarditis Associated with a New NLRP12 Mutation in a Male Adolescent

Idiopathic recurrent pericarditis (IRP) can be the hallmark of an autoinflammatory syndrome with recurrent attacks of chest pain and symptom-free intervals following an acute episode. The recurrence rate may be 35% in the pediatric population, frequently with less severe manifestations than at the first episode. Pericarditis can be the sole clinical manifestation or may be part of a systemic autoinflammatory disease (SAID), especially in the case of a recurrence. Familial Mediterranean Fever (FMF), Tumor Necrosis Factor Receptor-Associated Periodic Syndrome (TRAPS), Mevalonate-Kinase Deficiency (MKD), nucleotide-binding oligomerization domain 2 (NOD2)-associated autoinflammatory syndrome, and others are closely related to IRP based on similar clinical manifestations and treatment responses to anti-interleukin 1 (IL-1) agents, such as anakinra, and should therefore be excluded in patients with IRP. A newly described SAID, an autosomal dominant disorder known as NLRP12-AID (nucleotide-binding leucine-rich repeat-containing receptor 12-related autoinflammatory disease) is caused by heterozygous mutations in the NLRP12 gene and most commonly affects children. Fewer than 40 pediatric patients with NLRP12-AID have been described in the medical literature, with none presenting with RP. We report a case of relapsing pericarditis responsive to anti-IL-1 therapy in a male adolescent who carried a missense mutation in the NLRP12 gene potentially causative of the excessive activation of inflammatory pathways. This is a unique case in the medical literature that associates recurrent pericarditis in an adolescent presumed to be related to the missense mutation in the NLRP12 gene. The role of the NLRP12 inflammasome in generating and maintaining recurrent pericardial inflammation should be considered.

NLRP12-associated systemic autoinflammatory diseases in children

Systemic autoinflammatory diseases (SAIDs) are a group of monogenic diseases characterized by disordered innate immunity, which causes excessive activation of inflammatory pathways. Nucleotide-binding leucine-rich repeat-containing receptor 12-related autoinflammatory disease (NLRP12-AID) is a newly identified SAID and a rare autosomal dominant disorder caused by mutations in the NLRP12 gene, which is also known as familial cold autoinflammatory syndrome 2 (FCAS2) and mostly occurs in childhood. A total of 33 cases of NLRP12-AID in children and 21 different mutation types have been reported to date. The disease is mainly characterized by periodic fever, accompanied by multisystem inflammatory damage. NLRP12-AID is diagnosed through early clinical identification and genetic detection. Emerging drugs targeting interleukin-1-related inflammatory pathways are expected to change the treatment options and improve the quality of life of pediatric patients. This article aims to summarize the characteristics and pathogenesis of reported NLRP12-AID cases in children and provide ideas for clinical diagnosis and treatment.

Spectrum of Systemic Auto-Inflammatory Diseases in India: A Multi-Centric Experience

Background: Systemic autoinflammatory diseases (SAID) are rare inherited disorders involving genes regulating innate immune signaling and are characterized by periodic or chronic multi-systemic inflammation.

Objective: To describe spectrum of clinical, immunological, molecular features, and outcomes of patients with SAID in India.

Methods: Request to share data was sent to multiple centers in India that are involved in care and management of patients with Inborn Errors of Immunity. Six centers provided requisite data that were compiled and analyzed.

Results: Data on 107 patients with SAID were collated—of these, 29 patients were excluded due to unavailability of complete information. Twelve patients (15%) had type 1 interferonopathies, 21 (26%) had diseases affecting inflammasomes, 30 patients (41%) had non-inflammasome related conditions and 1five patients (19%) had Periodic Fever, Aphthous Stomatitis, Pharyngitis, Adenitis (PFAPA). Type1 interferonopathies identified in the cohort included patients with Deficiency of Adenosine Deaminase 2 (DADA2) (six patients; five families); STING-associated vasculopathy infantile-onset (SAVI) (three patients, one family); Spondyloenchondro-dysplasia with Immune Dysregulation (SPENCD) (two patients). Diseases affecting inflammasomes include Mevalonate Kinase Deficiency (eight patients); Cryopyrin-Associated Periodic Syndromes (CAPS) (seven patients); NLR Family, Pyrin domain-containing 12 (NLRP12) (two patients); Familial Mediterranean fever (FMF) (two patients); Autoinflammation and PLCG₂-associated antibody deficiency and immune dysregulation (APLAID) (two patients). TNF receptor-associated periodic syndrome (TRAPS) (three patients); A20 haploinsufficiency (four patients); Deficiency of Interleukin 1 Receptor Antagonist (DIRA) (two patients) were categorized as non-inflammasome related conditions. There were significant delays in diagnosis Corticosteroids and other immunosuppressive agents were used for treatment as anti-IL-1 drugs and other biological agents were and still are not available in India. Eight (16.3%) patients had so far succumbed to their illness.

Conclusions: This is the first nationwide cohort of patients with SAID from India. Clinical manifestations were diverse. Overlapping of clinical features with other relatively common rheumatological disorders often resulted in delays in diagnosis. More nationwide efforts are needed to enhance awareness of SAID among health care professionals and there is an urgent need to make targeted immunotherapies universally available.

The clinical phenotype and genotype of NLRP12-autoinflammatory disease: a Chinese case series with literature review

BACKGROUND

The nucleotide-binding oligomerization domain-like receptor protein 12 (NLRP12)-autoinflammatory disorder (NLRP12-AD) is a rare autoinflammatory disease characterized by recurrent fever, rash as well as musculoskeletal symptoms, which is rarely reported in Asian populations.

METHODS

Three cases of NLRP12-AD presented to our hospital were studied after parental consents were obtained. Clinical presentations were recorded on a standardized case report form. Mutations of NLRP12 were detected by primary immunodeficiency disease panels and further examined by Sanger sequencing. PubMed literature search for relevant studies of systemic autoinflammatory disorders, especially NLRP12-AD between January, 2000 and January, 2019 was carried and the clinical data were summarized. Comparisons were made between groups in terms of onset age and of ethnicity.

RESULTS

All our patients presented with fever, rash and arthritis/arthralgia, and sensorineural as well as sensorineural deafness (1/3), uveitis (1/3), abdominal pain (1/3), and myalgia (1/3). Two novel mutation variations, p.W581X and p.L558R, are reported here. In addition, we also found that two patients inherited the mutated alleles from their healthy parents, and this may be evidence of haploinsufficiency.

CONCLUSIONS

Although the genotypes are similar, the clinical manifestations between Chinese patients and Western patients vary thus highlighting the possible influence of ethnic and environmental factors. On the other hand, some genetic mutations may lead to specific phenotype, as we have found a high prevalence of sensorineural hearing loss among p.R284X patients.

NLRP12 gene mutations and auto-inflammatory diseases: ever-changing evidence

Systemic auto-inflammatory diseases (SAID) are a group of rare inherited conditions characterized by a dysregulation of the immune system and associated with recurrent episodes of fever and systemic inflammation. Patients with NLRP12 variants develop a rare autosomal dominant condition known as familial cold-induced autoinflammatory syndrome (FCAS2, OMIM #611762) that has been related to several different clinical manifestations including autoimmunity and immune deficiencies. In past years, several new variants have been described; however, their clinical relevance is sometimes uncertain, especially when they have been detected in healthy subjects. To our knowledge 61 patients with NLRP12 variants have been reported so far in the literature. Here we report the case of a 33-year-old woman with a history of recurrent fever and symmetric and additive poly-arthritis, fulfilling diagnostic criteria for RA, who was found to harbour two variants in the NLRP12 gene (OMIM *609648) and provide a review of the literature on similar cases.

The expanding pathways of autoinflammation: a lesson from the first 100 genes related to autoinflammatory manifestations

AutoInflammatory Diseases (AIDs) are a group of innate immune system disorders characterized by sterile inflammation without evidence of pathogenic autoantibodies or auto-reactive T lymphocytes. An expanding spectrum of genes and molecular pathways are associated with AIDs. Inflammasomopathies are secondary to dysregulation of multi-protein complexes, called inflammasomes, leading to an excessive maturation and secretion of IL1β and IL18. Patients present with persistent or recurrent systemic inflammation, abdominal and chest pain, skin rashes and are sensible to IL1 inhibitors. Unfolded proteins response causes a small number of AIDs that we propose to call immuno-proteinopathies, characterized by recurrent fevers and deep tissues inflammation. Other inflammatory conditions can occur in case of abnormalities of actin polymerization and the term of immuno-actinopathies is proposed. Generalized pustular psoriasis is a marker of autoinflammation mainly affecting the keratinocytes. Specific treatment targeting the p40 subunit of IL12 and IL23 or IL-17 are usually effective. Granulomatous inflammation characterizes AIDs related to NOD2 signaling defects. Defects in the ubiquitin-proteasome system cause a group of relopathies and some interferonopathies related to defect of the proteasome function (CANDLE syndrome). Gain of function of proteins regulating the production of type I interferons lead to severe inflammatory conditions, called interferonopathies. The JAK/STAT inhibitors are usually effective in these latter conditions. In conclusions, the identification of the main intracellular pathways involved in rare monogenic AIDs allows not only the proper classification of different conditions, but also highlight a pivotal role of possible novel therapeutic targets for the future.

Dermatologic and Dermatopathologic Features of Monogenic Autoinflammatory Diseases

Autoinflammatory diseases include disorders with a monogenic cause and also complex conditions associated to polygenic or multifactorial factors. An increased number of both monogenic and polygenic autoinflammatory conditions have been identified during the last years. Although skin manifestations are often predominant in monogenic autoinflammatory diseases, clinical and histopathological information regarding their dermatological involvement is still scarce. Monogenic autoinflammatory diseases with cutaneous expression can be classified based on the predominant lesion: (1) maculopapular rashes or inflammatory plaques; (2) urticarial rashes; (3) pustular, pyogenic or neutrophilic dermatosis-like rashes; (4) panniculitis or subcutaneous nodules; (5) vasculitis or vasculopathy; (6) hyperkeratotic lesions; (7) hyperpigmented lesions; (8) bullous lesions; and (9) aphthous lesions. By using this classification, this review intends to provide clinical and histopathological knowledge about cutaneous involvement in monogenic autoinflammatory diseases.