New workflow for classification of genetic variants' pathogenicity applied to hereditary recurrent fevers by the International Study Group for Systemic Autoinflammatory Diseases (INSAID).

BACKGROUND: Hereditary recurrent fevers (HRFs) are rare inflammatory diseases sharing similar clinical symptoms and effectively treated with anti-inflammatory biological drugs. Accurate diagnosis of HRF relies heavily on genetic testing. OBJECTIVES: This study aimed to obtain an experts' consensus on the clinical significance of gene variants in four well-known HRF genes: MEFV, TNFRSF1A, NLRP3 and MVK. METHODS: We configured a MOLGENIS web platform to share and analyse pathogenicity classifications of the variants and to manage a consensus-based classification process. Four experts in HRF genetics submitted independent classifications of 858 variants. Classifications were driven to consensus by recruiting four more expert opinions and by targeting discordant classifications in five iterative rounds. RESULTS: Consensus classification was reached for 804/858 variants (94%). None of the unsolved variants (6%) remained with opposite classifications (eg, pathogenic vs benign). New mutational hotspots were found in all genes. We noted a lower pathogenic variant load and a higher fraction of variants with unknown or unsolved clinical significance in the MEFV gene. CONCLUSION: Applying a consensus-driven process on the pathogenicity assessment of experts yielded rapid classification of almost all variants of four HRF genes. The high-throughput database will profoundly assist clinicians and geneticists in the diagnosis of HRFs. The configured MOLGENIS platform and consensus evolution protocol are usable for assembly of other variant pathogenicity databases. The MOLGENIS software is available for reuse at http://github.com/molgenis/molgenis; the specific HRF configuration is available at http://molgenis.org/said/. The HRF pathogenicity classifications will be published on the INFEVERS database at https://fmf.igh.cnrs.fr/ISSAID/infevers/.

Mosaicism in autoinflammatory diseases: Cryopyrin-associated periodic syndromes (CAPS) and beyond. A systematic review.

Autoinflammatory diseases (AIDs) are conditions related to defective regulation of the innate immune system. Sanger sequencing of the causative genes has long been the reference for confirming the diagnosis. However, for many patients with a typical AID phenotype, the genetic cause remains unknown. A pioneering study in 2005 demonstrated mosaicism in patients with cryopyrin-associated periodic syndromes (CAPS); the authors found somatic mosaicism in 69% of their cohort of Sanger-negative CAPS patients. We aim to address the extent to which mosaicism contributes to the etiology of AIDs and its impact on phenotype. We retrieved English-language publications reporting mosaicism in AIDs by querying PubMed with no restriction on date and we surveyed French reference centers. We provide a comprehensive clinical and genetic picture of mosaicism in AIDs. We estimate that the proportion of CAPS-like patients presenting mosaicism ranges from 0.5% to 19%. We also discuss the possible links between the proportion of mutated alleles and various clinical features. This review reevaluates the contribution of mosaic DNA variants in CAPS. Mosaicism may be more common than anticipated in other AIDs. No significant difference was demonstrated between variant allele frequency and clinical phenotype. Such knowledge has implications for the development of guidelines for genetic diagnosis, genetic counseling of affected families and effective patient care.

A new autoinflammatory and autoimmune syndrome associated with NLRP1 mutations: NAIAD (NLRP1-associated autoinflammation with arthritis and dyskeratosis).

OBJECTIVES: Inflammasomes are multiprotein complexes that sense pathogens and trigger biological mechanisms to control infection. Nucleotide-binding oligomerisation domain-like receptor (NLR) containing a PYRIN domain 1 (NLRP1), NLRP3 and NLRC4 plays a key role in this innate immune system by directly assembling in inflammasomes and regulating inflammation. Mutations in NLRP3 and NLRC4 are linked to hereditary autoinflammatory diseases, whereas polymorphisms in NLRP1 are associated with autoimmune disorders such as vitiligo and rheumatoid arthritis. Whether human NLRP1 mutation is associated with autoinflammation remains to be determined. METHODS: To search for novel genes involved in systemic juvenile idiopathic arthritis, we performed homozygosity mapping and exome sequencing to identify causative genes. Immunoassays were performed with blood samples from patients. RESULTS: We identified a novel disease in three patients from two unrelated families presenting diffuse skin dyskeratosis, autoinflammation, autoimmunity, arthritis and high transitional B-cell level. Molecular screening revealed a non-synonymous homozygous mutation in NLRP1 (c.2176C>T; p.Arg726Trp) in two cousins born of related parents originating from Algeria and a de novo heterozygous mutation (c.3641C>G, p.Pro1214Arg) in a girl of Dutch origin. The three patients showed elevated systemic levels of caspase-1 and interleukin 18, which suggested involvement of NLRP1 inflammasome. CONCLUSIONS: We demonstrate the responsibility of human NLRP1 in a novel autoinflammatory disorder that we propose to call NAIAD for NLRP1-associated autoinflammation with arthritis and dyskeratosis. This disease could be a novel autoimmuno-inflammatory disease combining autoinflammatory and autoimmune features. Our data, combined with that in the literature, highlight the pleomorphic role of NLRP1 in inflammation and immunity. TRIAL REGISTRATION NUMBER: NCT02067962; Results.

Mutation Update for COL2A1 Gene Variants Associated with Type II Collagenopathies.

Mutations in the COL2A1 gene cause a spectrum of rare autosomal-dominant conditions characterized by skeletal dysplasia, short stature, and sensorial defects. An early diagnosis is critical to providing relevant patient care and follow-up, and genetic counseling to affected families. There are no recent exhaustive descriptions of the causal mutations in the literature. Here, we provide a review of COL2A1 mutations extracted from the Leiden Open Variation Database (LOVD) that we updated with data from PubMed and our own patients. Over 700 patients were recorded, harboring 415 different mutations. One-third of the mutations are dominant-negative mutations that affect the glycine residue in the G-X-Y repeats of the alpha 1 chain. These mutations disrupt the collagen triple helix and are common in achondrogenesis type II and hypochondrogenesis. The mutations resulting in a premature stop codon are found in less severe phenotypes such as Stickler syndrome. The p.(Arg275Cys) substitution is found in all patients with COL2A1-associated Czech dysplasia. LOVD-COL2A1 provides support and potential collaborative material for scientific and clinical projects aimed at elucidating phenotype-genotype correlation and differential diagnosis in patients with type II collagenopathies.

Mutation Update for Kabuki Syndrome Genes KMT2D and KDM6A and Further Delineation of X-Linked Kabuki Syndrome Subtype 2.

Kabuki syndrome (KS) is a rare but recognizable condition that consists of a characteristic face, short stature, various organ malformations, and a variable degree of intellectual disability. Mutations in KMT2D have been identified as the main cause for KS, whereas mutations in KDM6A are a much less frequent cause. Here, we report a mutation screening in a case series of 347 unpublished patients, in which we identified 12 novel KDM6A mutations (KS type 2) and 208 mutations in KMT2D (KS type 1), 132 of them novel. Two of the KDM6A mutations were maternally inherited and nine were shown to be de novo. We give an up-to-date overview of all published mutations for the two KS genes and point out possible mutation hot spots and strategies for molecular genetic testing. We also report the clinical details for 11 patients with KS type 2, summarize the published clinical information, specifically with a focus on the less well-defined X-linked KS type 2, and comment on phenotype-genotype correlations as well as sex-specific phenotypic differences. Finally, we also discuss a possible role of KDM6A in Kabuki-like Turner syndrome and report a mutation screening of KDM6C (UTY) in male KS patients.

French practical guidelines for the diagnosis and management of AA amyloidosis.

AA amyloidosis is secondary to the deposit of excess insoluble Serum Amyloid A (SAA) protein fibrils. AA amyloidosis complicates chronic inflammatory diseases, especially chronic inflammatory rheumatisms such as rheumatoid arthritis and spondyloarthritis; chronic infections such as tuberculosis, bronchectasia, chronic inflammatory bowel diseases such as Crohn's disease; and auto-inflammatory diseases including familial Mediterranean fever. This work consists of the French guidelines for the diagnosis workup and treatment of AA amyloidosis. We estimate in France between 500 and 700 cases in the whole French population, affecting both men and women. The most frequent organ impaired is kidney which usually manifests by oedemas of the lower extremities, proteinuria, and/or renal failure. Patients are usually tired and can display digestive features anf thyroid goiter. The diagnosis of AA amyloidosis is based on detection of amyloid deposits on a biopsy using Congo Red staining with a characteristic green birefringence in polarized light. Immunohistochemical analysis with an antibody directed against Serum Amyloid A protein is essential to confirm the diagnosis of AA amyloidosis. Peripheral inflammatory biomarkers can be measured such as C Reactive protein and SAA. We propose an algorithm to guide the etiological diagnosis of AA amyloidosis. The treatement relies on the etiologic treatment of the undelying chronic inflammatory disease to decrease and/or normalize Serum Amyloid A protein concentration in order to stabilize amyloidosis. In case of renal failure, dialysis or even a kidney transplant can be porposed. Nowadays, there is currently no specific treatment for AA amyloidosis deposits which constitutes a therapeutic challenge for the future.

Case Report: Persistency Pneumococcal Polysaccharide in Cerebrospinal Fluid During a Post Pneumococcal Chronic Aseptic Meningitis: Coincidental or (Auto-)Inflammatory Embers.

We report the case of a 9-months-old boy that has presented a steroid-dependent post-pneumococcal chronic aseptic meningitis was associated with persistence of pneumococcal cell wall components in cerebrospinal fluid during more than 20 months. Suggesting that this antigenic persistence could be involved in post-infectious manifestations through innate immunity response.

Evaluation of post-infectious inflammatory reactions in a retrospective study of 3 common invasive bacterial infections in pediatrics.

Infectious diseases can result in unanticipated post-infectious inflammatory reactions (PIIR). Our aim was to explore PIIR in 3 frequent pediatric bacterial invasive infections in France by a retrospective monocentric study. We included children hospitalized between 2003 and 2012 for Streptococcus pneumoniae (SP), Neisseria meningitidis (NM), or Streptococcus pyogenes invasive infections. The PIIR had to have occurred between 3 and 15 days without fever despite an individually tailored antibiotic therapy. A descriptive analysis was carried out to determine PIIR risk factors. We included 189 patients, of whom 72, 79, and 38 exhibited invasive infections caused by S pyogenes, SP, and NM, respectively. The mean age was 44 months. PIIR were observed in 39 cases, occurring after a median of 8 days (5-12), with a median duration of 3 days (2-6). Fever, arthritis, and pleural effusion were observed in 87%, 28.2%, and 25.6%, respectively. In multivariate analysis, PIIR were associated with pleuropneumonia, hospitalization in an intensive care unit (ICU), and elevated C-reactive protein (CRP). PIIR were observed in 20% of children after SP, NM, or S pyogenes invasives infections. Their occurrence was associated with the initial severity but not the etiological microorganism. Further studies are warranted to confirm these findings.