A critical region of A20 unveiled by missense TNFAIP3 variations that lead to autoinflammation.

A20 haploinsufficiency (HA20) is an autoinflammatory disease caused by heterozygous loss-of-function variations in TNFAIP3, the gene encoding the A20 protein. Diagnosis of HA20 is challenging due to its heterogeneous clinical presentation and the lack of pathognomonic symptoms. While the pathogenic effect of TNFAIP3 truncating variations is clearly established, that of missense variations is difficult to determine. Herein, we identified a novel TNFAIP3 variation, p.(Leu236Pro), located in the A20 ovarian tumor (OTU) domain and demonstrated its pathogenicity. In the patients' primary cells, we observed reduced A20 levels. Protein destabilization was predicted in silico for A20_Leu236Pro and enhanced proteasomal degradation was confirmed in vitro through a flow cytometry-based functional assay. By applying this approach to the study of another missense variant, A20_Leu275Pro, for which no functional characterization has been performed to date, we showed that this variant also undergoes enhanced proteasomal degradation. Moreover, we showed a disrupted ability of A20_Leu236Pro to inhibit the NF-κB pathway and to deubiquitinate its substrate TRAF6. Structural modeling revealed that two residues involved in OTU pathogenic missense variations (i.e. Glu192Lys and Cys243Tyr) establish common interactions with Leu236. Interpretation of newly identified missense variations is challenging, requiring, as illustrated here, functional demonstration of their pathogenicity. Together with functional studies, in silico structure analysis is a valuable approach that allowed us (i) to provide a mechanistic explanation for the haploinsufficiency resulting from missense variations and (ii) to unveil a region within the OTU domain critical for A20 function.

Pharmacological options in the treatment of osteogenesis imperfecta: A comprehensive review of clinical and potential alternatives.

Osteogenesis imperfecta (OI) is a genetically heterogeneous connective tissue disorder characterized by bone fragility and different extra-skeletal manifestations. The severity of these manifestations makes it possible to classify OI into different subtypes based on the main clinical features. This review aims to outline and describe the current pharmacological alternatives for treating OI, grounded on clinical and preclinical reports, such as antiresorptive agents, anabolic agents, growth hormone, and anti-TGFß antibody, among other less used agents. The different options and their pharmacokinetic and pharmacodynamic properties will be reviewed and discussed, focusing on the variability of their response and the molecular mechanisms involved to attain the main clinical goals, which include decreasing fracture incidence, improving pain, and promoting growth, mobility, and functional independence.

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.

De Novo Gain-Of-Function Variations in LYN Associated With an Early-Onset Systemic Autoinflammatory Disorder.

OBJECTIVE: To identify the molecular basis of a severe systemic autoinflammatory disorder (SAID) and define its main phenotypic features, and to functionally assess the sequence variations identified in LYN, a gene encoding a nonreceptor tyrosine kinase. METHODS: We used targeted next-generation sequencing and in vitro functional studies of Lyn phosphorylation state and Lyn-dependent NF-κB activity after expression of recombinant Lyn isoforms carrying different sequence variations. RESULTS: We identified a de novo LYN variation (p.Tyr508His) in a patient presenting since birth with recurrent fever, chronic urticaria, atopic dermatitis, arthralgia, increased inflammatory biomarkers, and elevated plasma cytokine levels. We studied the consequences on Lyn phosphorylation state of the p.Tyr508His variation and of the 2 LYN variations reported so far (p.Tyr508Phe and p.Tyr508*), and found that all 3 variations prevent phosphorylation of residue 508 and lead to autophosphorylation of Tyr397. Additionally, these 3 LYN variations activate the NF-κB pathway. These results show a gain-of-function effect of the variations involving Tyr508 on Lyn activity. CONCLUSION: This study demonstrates the pathogenicity of the first 3 LYN variations identified in SAID patients and delineates the phenotypic spectrum of a disease entity characterized by severe, early-onset, systemic inflammatory disease affecting neonates with no family history of SAID. All 3 LYN variations affect the same tyrosine residue located in the C-terminus of Lyn, thereby demonstrating the critical role of this residue in the proper regulation of Lyn activity in humans.

Role of non-invasive methods in detecting liver impairment in familial Mediterranean fever adult patients with persistent hepatic cytolysis.

Familial Mediterranean fever (FMF) patients may have hepatic cytolysis, although its origin is not formally elucidated. We aimed to evaluate liver involvement in familial Mediterranean fever (FMF) using non-invasive methods. All adult FMF patients harboring two non-ambiguous mutations of the MEFV gene with hepatic cytolysis were identified in a French tertiary adult center for FMF. Liver impairment was explored with FibroMax (a non-invasive method to estimate hepatic steatosis, necrosis, inflammation and fibrosis) and liver ultrasound. Among 520 FMF adult patients, 43 had persistent hepatic cytolysis and 20 patients were included (11 women, median age at inclusion: 49.5 years). According to the FibroMax results, patients were classified as having steatosis, fibrosis, and possible or definite nonalcoholic steato-hepatitis in 10 (50%), 9 (45%) and 7 (35%) of cases, respectively. The score of steatosis did not seem associated with the usual metabolic risk factors. No significant association was found between the cumulated dose of colchicine and any of the scores included in FibroMax. In adult FMF patients with persistent hepatic cytolysis, steatosis is the first cause to consider even in the absence of usual metabolic risk factors, suggesting other mechanisms. Colchicine did not seem to be involved in this toxicity.

RNF213-associated urticarial lesions with hypercytokinemia.

BACKGROUND: Urticarial lesions are observed in both cutaneous and systemic disorders. Familial forms of urticarial syndromes are rare and can be encountered in systemic autoinflammatory diseases. OBJECTIVE: We sought to investigate a large family with dominantly inherited chronic urticarial lesions associated with hypercytokinemia. METHODS: We performed a genetic linkage analysis in 14 patients from a 5-generation family, as well as whole-exome sequencing, cytokine profiling, and transcriptomic analyses on samples from 2 patients. The identified candidate protein was studied after in vitro expression of the corresponding normal and mutated recombinant proteins. An unsupervised proteomic approach was used to unveil the associated protein network. RESULTS: The disease phenotype of the most affected family members is characterized by chronic urticarial flares associated with extremely high plasma levels of proinflammatory (IL-1ß, IL-6, and TNF-α) and anti-inflammatory (IL-10 and IL-1 receptor antagonist [IL-1RA]) cytokines, with no secondary organ dysfunction, no susceptibility to infections, no fever, and normal C-reactive protein levels. Monocyte transcriptomic analyses identified an immunotolerant profile in the most affected patient. The affected family members carried a loss-of-function mutation in RNF213 that encodes mysterin, a protein with a poorly known physiologic role. We identified the deubiquitinase CYLD, a major regulator of inflammation, as an RNF213 partner and showed that CYLD expression is inhibited by wild-type but not mutant RNF213. CONCLUSION: We identified a new entity characterized by chronic urticarial lesions associated with a clinically blunted hypercytokinemia. This disease, which is due to loss of function of RNF213, reveals mysterin's key role in the complex molecular network of innate immunity.

The recurrent TCF4 missense variant p.(Arg389Cys) causes a neurodevelopmental disorder overlapping with but not typical for Pitt-Hopkins syndrome.

TCF4 haploinsufficiency by deletions, truncating variants or loss-of-function missense variants within the DNA-binding and protein interacting bHLH domain causes Pitt-Hopkins syndrome (PTHS). This neurodevelopmental disorder (NDD) is characterized by severe intellectual disability (ID), epilepsy, hyperbreathing and a typical facial gestalt. Only few aberrations of the N-terminus of TCF4 were associated with milder or atypical phenotypes. By personal communication and searching databases we assembled six cases with the novel, recurrent, de novo missense variant c.1165C > T, p.(Arg389Cys) in TCF4. This variant was identified by diagnostic exome or panel sequencing and is located upstream of the bHLH domain. All six individuals presented with moderate to severe ID with language impairment. Microcephaly occurred in two individuals, epilepsy only in one, and no breathing anomalies or myopia were reported. Facial gestalt showed some aspects of PTHS but was rather non-specific in most individuals. Interestingly, the variant is located within the AD2 activation domain next to a highly conserved coactivator-recruitment motif and might alter interaction with coactivator proteins independently from the bHLH domain. Our findings of a recurrent missense variant outside the bHLH domain in six individuals with an ID phenotype overlapping with but not typical for PTHS delineate a novel genotype-phenotype correlation for TCF4-related NDDs.

Mosaic variants in TNFRSF1A: an emerging cause of tumour necrosis factor receptor-associated periodic syndrome.

OBJECTIVE: To identify the molecular basis of a systemic autoinflammatory disorder (SAID) evocative of TNF receptor-associated periodic syndrome (TRAPS). METHODS: (i) Deep next generation sequencing (NGS) through a SAID gene panel; (ii) variant allele distribution in peripheral blood subpopulations; (iii) in silico analyses of mosaic variants using TNF receptor superfamily 1A (TNFRSF1A) crystal structure; (iv) review of the very rare TNFRSF1A mosaic variants reported previously. RESULTS: In a 36-year-old man suffering from recurrent fever for 12 years, high-depth NGS revealed a TNFRSF1A mosaic variant, c.176G>A p.(Cys59Tyr), which Sanger sequencing failed to detect. This mosaic variant displayed a variant allele fraction of 14% in whole blood; it affects both myeloid and lymphoid lineages. p.(Cys59Tyr), a recurrent germline pathogenic variant, affects a crucial cysteine located in the first cysteine-rich domain (CRD1) and involved in a disulphide bridge. Introduction of a tyrosine at this position is expected to disrupt the CRD1 structure. Review of the three previously reported TNFRSF1A mosaic variants revealed that they are all located in a small region of CRD2 and that germinal cells can be affected. CONCLUSION: This study expands the localization of TNFRSF1A mosaic variants to the CRD1 domain. Noticeably, residues involved in germline TNFRSF1A mutational hot spots can also be involved in post-zygotic mutational events. Including our study, only four patients have been thus far reported with TNFRSF1A mosaicism, highlighting the need for a high-depth NGS-based approach to avoid the misdiagnosis of TRAPS. Genetic counselling has to consider the potential occurrence of TNFRSF1A mosaic variants in germinal cells.

AA amyloidosis complicating cryopyrin-associated periodic syndrome: a study of 86 cases including 23 French patients and systematic review.

OBJECTIVE: Cryopyrin-associated periodic syndrome (CAPS) is a rare but treatable inherited autoinflammatory condition including familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS) and chronic infantile neurologic cutaneous articular syndrome (CINCA). Our objective was to describe the main features of CAPS AA amyloidosis (AA-CAPS) associated and the efficacy of IL-1 inhibitors in this indication. METHODS: Retrospective study in France associated with a systematic literature review. RESULTS: Eighty-six patients were identified: 23 new French cases and 63 from the literature, with a median age at amyloidosis diagnosis of 39 years old. CAPS subtypes were MWS (n = 62), FCAS (n = 9), frontier forms between MWS and FCAS (n = 12) and between CINCA and MWS (n = 3). NLRP3 had been sequenced in 60 patients (70%) and the most frequent mutation was R260W (60%). Three AA-CAPS patients displayed somatic NLRP3 mutations. Death occurred in 35 patients (41%), none of whom having ever received IL-1 inhibitors. Twenty-eight patients (33%) received IL-1 inhibitors, with a >50% decrease in proteinuria in 89% of cases. CONCLUSION: AA amyloidosis can occur in nearly all CAPS subtypes. IL-1 inhibitors are effective, underlining the necessity of an early diagnosis of CAPS in order to start this treatment as soon as possible among AA-CAPS patients.

Two new cases of interstitial 7q35q36.1 deletion including CNTNAP2 and KMT2C.

BACKGROUND: Terminal deletions of the long arm of chromosome 7 are well known and frequently associated with syndromic holoprosencephaly due to the involvement of the SHH (aliases HHG1, SMMCI, TPT, TPTPS, and MCOPCB5) gene region. However, interstitial deletions including CNTNAP2 (aliases Caspr2, KIAA0868, and NRXN4) and excluding the SHH region are less common. METHODS: We report the clinical and molecular characterization associated with pure 7q35 and 7q35q36.1 deletion in two unrelated patients as detected by oligonucleotide-based array-CGH analysis. RESULTS: The common clinical features were abnormal maternal serum screening during first-trimester pregnancy, low occipitofrontal circumference at birth, hypotonia, abnormal feet, developmental delay, impaired language development, generalized seizures, hyperactive behavior, friendly personality, and cranio-facial dysmorphism. Both deletions occurred de novo and sequencing of CNTNAP2, a candidate gene for epilepsy and autism showed absence of mutation on the contralateral allele. CONCLUSION: Combined haploinsufficiency of GALNTL5 (alias GalNAc-T5L), CUL1, SSPO (aliases SCO-spondin, KIAA0543, and FLJ36112), AOC1 (alias DAO), RHEB, and especially KMT2C (alias KIAA1506 and HALR) with monoallelic disruption of CNTNAP2 may explain neurologic abnormalities, hypotonia, and exostoses. Haploinsufficiency of PRKAG2 (aliases AAKG, AAKG2, H91620p, WPWS, and CMH6) and KCNH2 (aliases Kv11.1, HERG, and erg1) genes may be responsible of long QT syndrome observed for one patient.

Chronic hepatic involvement in the clinical spectrum of A20 haploinsufficiency.

BACKGROUND & AIMS: Secondary to tumour necrosis factor-alpha induced protein 3 (TNFAIP3) mutations, A20 haploinsufficiency (HA20) is a recently described autoinflammatory disease with clinical features similar to those of Behçet's and Crohn's diseases but with a constantly expanding clinical spectrum. Here, we describe HA20 liver involvement in three new patients from the same family. METHODS: We retrospectively assessed clinical, biological and/or histological findings for eight patients over three generations of the same family with heterozygous mutations in the TNFAIP3 gene (c.259C > T, p.Arg87*). RESULTS: The eight patients exhibited the following: aphthous ulcers (8/8, bipolar in 7), autoimmune features (6/8, including 5 with definitive autoimmune disease diagnoses, ie, type I diabetes, Hashimoto thyroiditis, pernicious anaemia, and/or 5 with antinuclear antibodies ≥320), pustulosis/folliculitis (5/8), abdominal pain (4/8), arthralgia (3/8), enlarged cervical lymph nodes (3/8) and pericarditis (1/8). In addition, three patients (twin sisters and their grandmother aged 23 and 70 years, respectively) exhibited persistent mild hepatic cytolysis associated with splenomegaly (n = 3), hepatomegaly (n = 1) and/or liver atrophy (n = 1) on echography. We could not detect any other causes of chronic liver diseases. Liver biopsies from three patients displayed hepatic fibrosis, hepatocyte injury and/or CD4+ /CD8+ T lymphocyte infiltration, and patterns of inflammatory cells and NLRP3 or NF-κB immunostaining differed from the predominant neutrophil infiltration observed in skin or some digestive tract biopsies. CONCLUSIONS: This study reinforces the dual involvement of innate and adaptive immunity in HA20 according to both acute and chronic injury and the organ involved and widens its clinical spectrum to include chronic hepatic involvement.

Tumour necrosis factor receptor-1 associated periodic syndrome (TRAPS)-related AA amyloidosis: a national case series and systematic review.

OBJECTIVES: TNF receptor-1-associated periodic syndrome (TRAPS) is a rare autosomal dominant autoinflammatory disorder associated with mutations in the TNF receptor super family 1 A (TNFRSF1A) gene. AA amyloidosis (AA) is the most severe complication of TRAPS. To study the occurrence and prognosis of AA in TRAPS, we conducted a retrospective study of all French cases and a systematic literature review. METHODS: This case series includes TRAPS patients followed by our centre from 2000 to 2020 presenting with histologically confirmed AA. We conducted a systematic literature review on the PubMed and EMBASE databases for articles published up to February 2021 following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines and using the keywords: amyloidoisis, amyloid, TNF receptor-associated periodic syndrome, TNF receptor-associated periodic syndrome, tumor necrosis factor receptor-associated periodic syndrome, TRAPS, TNFRSF1A, familial hibernian fever and hibernian familial fever. RESULTS: A total of 41 TRAPS with AA were studied: three new patients and 38 cases from the literature. AA diagnosis preceded that of TRAPS in 96% of cases, and 17/36 (47%) required renal replacement therapy. Death occurred in 5/36 (14%) with a median follow-up of 23 months. Effect of biologics on AA were available for 21 regimens in 19 patients: 10 improved renal function, seven stabilized and four worsened. Four patients (36% of transplanted patients) relapse AA on kidney graft (only one under etanercept). CONCLUSION: TRAPS is revealed by AA in most cases. Therefore, clinical features of TRAPS should be screened for in AA patients. IL-1 antagonist can help to normalize inflammation and to preserve renal function.

Association between familial Mediterranean fever and multiple sclerosis: A case series from the JIR cohort and systematic literature review.

INTRODUCTION: Familial Mediterranean fever (FMF) is the most frequent monogenic autoinflammatory disorder; and leads to the uncontrolled production of interleukin (IL)-1ß. Multiple sclerosis (MS) is an inflammatory disease of the central nervous system; and its development seems to be partly correlated with IL-1ß levels. It is hypothesized that FMF could be associated with MS. We aim to describe the features of patients displaying both diseases and to investigate the MEFV mutation rate in MS patients. METHODS: Patients with definite MS were retrieved from the cohort of FMF patients in the Reference Center for Rare Auto-inflammatory Diseases and Amyloidosis (CEREMAIA). We also performed a systematic literature review of articles from PubMed that were published from 1990 to 2020. RESULTS: Twenty-four patients were included in the case series: five patients (1.3%) from our cohort of 364 and 19 patients from the literature. The sex ratio was 2:1. The mean age at diagnosis of FMF was 19 years old; and that for MS was 29 years old. Seven studies investigating the MEFV mutation rate in MS patients were included. Three studies found a higher mutation rate in MS patients than in the control group. CONCLUSION: FMF and MS features were comparable to those of patients with unrelated diseases; and MEFV mutation carriage was not positively correlated with MS. However; MS prevalence in FMF patients was higher than was expected in a healthy population. To a lesser extent; FMF prevalence in MS patients was higher than expected in a healthy population and the difference might not be significant. These data suggest that FMF could be associated with MS; and further studies are needed to investigate a potential causal association.

"Helicobacter pylori in familial mediterranean fever: A series of 120 patients from literature and from france".

INTRODUCTION: Familial Mediterranean Fever (FMF), the most common monogenic auto-inflammatory disease, is characterized by recurrent febrile abdominal pain. Helicobacter pylori infection (HPI), one of the most frequent infections worldwide, can mimic an FMF attack. OBJECTIVES: Identify FMF patients with HPI in a cohort of French FMF patients and the literature and identify features allowing to distinguish HPI from an FMF attack. METHODS: A retrospective study of all HPI cases was performed on the cohort of FMF patients fulfilling the Livneh criteria from the French Reference Center for rare Auto-Inflammatory Diseases and Amyloidosis (CEREMAIA). A systematic literature review of HPI in FMF patients was conducted according to the PRISMA guidelines. RESULTS: Eight French patients developed HPI, whose symptoms of epigastralgia, diarrhea, anorexia/weight loss, and nausea/vomiting differed from their typical abdominal FMF attacks. A total of 112 FMF patients with HPI have been described in the literature, including 61 adults. Diagnosis of HPI was made by gastroscopy (n = 43), labelled urea test (n = 55) or IgG serology by ELISA (n = 12). When performed, C-reactive protein was always elevated. Ten cases of interaction between colchicine and antibiotic therapy for HPI (clarithromycin (n = 9) and azithromycin (n = 1)) were reported. CONCLUSION: We described a total of 120 patients with typical FMF and HPI. When FMF patients develop atypical abdominal symptoms, upper gastrointestinal endoscopy with biopsies is essential to eliminate underlying HPI. Untreated HPI can lead to misdiagnosis of colchicine resistance with inappropriate prescription of an interleukin-1 inhibitor at a non-negligible cost.

Fast diagnostic test for familial Mediterranean fever based on a kinase inhibitor.

BACKGROUND AND OBJECTIVE: Familial Mediterranean fever (FMF) is the most frequent hereditary autoinflammatory disease. Its diagnosis relies on a set of clinical criteria and a genetic confirmation on identification of biallelic pathogenic MEFV variants. MEFV encodes pyrin, an inflammasome sensor. Using a kinase inhibitor, UCN-01, we recently identified that dephosphorylation of FMF-associated pyrin mutants leads to inflammasome activation. The aim of this study was to assess whether quantifying UCN-01-mediated inflammasome activation could discriminate FMF patients from healthy donors (HD) and from patients with other inflammatory disorders (OID). METHODS: Real-time pyroptosis and IL-1ß secretion were monitored in response to UCN-01 in monocytes from FMF patients (n=67), HD (n=71) and OID patients (n=40). Sensitivity and specificity of the resulting diagnostic tests were determined by receiver operating characteristic curve analyses. RESULTS: Inflammasome monitoring in response to UCN-01 discriminates FMF patients from other individuals. Pyroptosis assessment leads to a fast FMF diagnosis while combining pyroptosis and IL-1ß dosage renders UCN-01-based assays highly sensitive and specific. UCN-01-triggered monocytes responses were influenced by MEFV gene dosage and MEFV mutations in a similar way as clinical phenotypes are. CONCLUSIONS: UCN-01-based inflammasome assays could be used to rapidly diagnose FMF, with high sensitivity and specificity.

Mowat Wilson syndrome and Hirschsprung disease: a retrospective study on functional outcomes.

AIM OF THE STUDY: Mowat Wilson syndrome (MWS) is a complex genetic disorder due to mutation or deletion of the ZEB2 gene (ZFHX1B), including multiple clinical features. Hirschsprung disease is associated with this syndrome with a prevalence between 43 and 57%. The aim of this study was to demonstrate the severe outcomes and the high complication rates in children with MWS, focusing on their complicated follow-up. METHODS: A retrospective comparative study was conducted on patients referred to Robert-Debré Children's Hospital for MWS from 2003 to 2018. Multidisciplinary follow-up was carried out by surgeons, geneticists, gastroenterologists, and neurologists. Data regarding patient characteristics, surgical management, postoperative complications, and functional outcomes were collected. RESULTS: Over this period of 15 years, 23 patients were diagnosed with MWS. Hirschsprung disease was associated with 10 of them (43%). Of these cases, two patients had recto-sigmoïd aganglionosis (20%), three had aganglionic segment extension to the left colic angle (30%), two to the right colic angle (20%), and three to the whole colon (30%). The median follow-up was 8.5 years (2 months-15 years). All patients had seizures and intellectual disability. Six children (60%) presented with cardiac defects. At the last follow-up, three patients still had a stoma diversion and 7 (70%) were fed orally. One patient died during the first months. Eight (80%) of these children required a second surgery due to complications. At the last follow-up, three patients reported episodes of abdominal bloating (42%), one recurrent treated constipation (14.3%), and one soiling (14.3%). Genetic analysis identified three patients with heterozygous deletions, three with codon mutations, and three with frameshift mutations. CONCLUSIONS: MWS associated with Hirschsprung disease has a high rate of immediate surgical complications but some patients may achieve bowel function comparable with non-syndromic HD patients. A multidisciplinary follow-up is required for these patients. LEVEL OF EVIDENCE: Retrospective observational single cohort study, Level 3.

AA amyloidosis revealing mevalonate kinase deficiency: A report of 20 cases including two new French cases and a comprehensive review of literature.

INTRODUCTION: Mevalonate kinase deficiency (MKD) is a rare autosomal recessive autoinflammatory disease that can lead to an inflammatory A amyloidosis (AA). METHODS: To study the occurrence of AA in MKD patients we performed a systemic review of the literature and described two novel patients. RESULTS: Amyloidosis occurred in 20 MKD patients, renal impairment being always the revealing symptom of AA. Although an accurate prevalence estimation is not possible since exact MKD prevalence is unknown, AA seems rare in MKD (about 6% if we estimate MKD prevalence at 300 patients worldwide). MVK gene study, available in 18 out of the 20 patients, confirmed two pathogenic mutations in all tested individuals. The most frequent genotype was V377I/I268T (n = 9/18). Retrospective search of clinical signs of MKD established, in all patients carrying MVK pathogenic mutations, a disease onset within the first four years of life. Nephrotic syndrome (n = 15), end-stage renal failure (n = 5) or both (n = 8) pointed out kidney amyloidosis. The youngest patient with renal amyloidosis was a European four-year-old girl previously misdiagnosed with PFAPA syndrome. Five patients died of AA amyloidosis despite the use of a biotherapy for two of them; kidney transplant was performed in nine individuals. Colchicine was not effective in any patient. Anti-interleukin-1 anakinra (n = 8), anti TNF etanercept (n = 7) and anti-interleukin 6 tocilizumab (n = 5) treatments were partially effective. CONCLUSION: Inflammatory A amyloidosis, a rare complication of MKD, can cause death or necessitate kidney transplantation. Early diagnosis and cytokine blocking biotherapy using anti-IL1, anti-TNF or anti-IL6 agents are required to prevent terminal renal failure.

Typical Familial Mediterranean Fever associated with the heterozygous missense sequence p.T577N variant of the MEFV gene: Report on two Northern European Caucasians relatives in France.

INTRODUCTION: Familial Mediterranean fever is the most frequent monogenic auto-inflammatory disorder that mostly affects Mediterranean population. Although this auto-inflammatory disease has historically been described as a recessive genetic disorder with homozygous or compound heterozygous mutations in the MEFV gene, an increasing number of cases are described with the detection of new single MEFV gene heterozygous mutations with modern molecular techniques. CASE DESCRIPTION: We report the cases of Caucasian French descent father and daughter who exhibited joint and abdominal inflammatory attacks resembling Familial Mediterranean Fever. Genetic studies revealed in both a heterozygous mutation p.T577N in exon 8 of MEFV gene, and in which colchicine was effective for preventing the attacks. CONCLUSION: Single heterozygous mutation of MEFV can be responsible for typical Familial Mediterranean Fever clinical pattern and, what is more, in non-Mediterranean ethnic background patients.