A novel missense mutation (C30S) in the gene encoding tumor necrosis factor receptor 1 linked to autosomal-dominant recurrent fever with localized myositis in a French family

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.

Monogenic autoinflammatory diseases in children: single center experience with clinical, genetic, and imaging review

Purpose

1. To review the contemporary literature and present a list of the imaging findings for patients with autoinflammatory diseases from our hospital. All these patients are found to have a genetic mutation that is responsible for their disease.

2. To present follow-up imaging findings, when available, and correlate those with symptoms and type of treatment administered in approximately 40 patients with autoinflammatory diseases of a single tertiary pediatric health care center including familial Mediterranean fever, Cryopyrin-associated autoinflammatory syndrome, PAPA (pyogenic arthritis, pyoderma gangrenousum, and acne) syndrome, and more. These findings are related to disease progression, treatment response, or treatment-induced changes.

Conclusion

Autoinflammatory diseases are relatively rare entities that can affect any system of the body. Given the many nonspecific imaging features, awareness of these diseases and good communication with clinicians aid in reaching an accurate diagnosis.

Autoinflammatory diseases in childhood, part 1: monogenic syndromes

Autoinflammatory diseases constitute a family of disorders defined by aberrant stimulation of inflammatory pathways without involving antigen-directed autoimmunity. They may be divided into monogenic and polygenic types. Monogenic autoinflammatory syndromes are those with identified genetic mutations, such as familial Mediterranean fever, tumor necrosis factor receptor-associated periodic fever syndrome (TRAPS), mevalonate kinase deficiency or hyperimmunoglobulin D syndrome, cryopyrin-associated periodic fever syndromes (CAPS), pyogenic arthritis pyoderma gangrenosum and acne (PAPA) syndrome, interleukin-10 and interleukin-10 receptor deficiencies, adenosine deaminase 2 deficiency and pediatric sarcoidosis. Those without an identified genetic mutation are known as polygenic and include systemic-onset juvenile idiopathic arthritis, idiopathic recurrent acute pericarditis, Behçet syndrome, chronic recurrent multifocal osteomyelitis and inflammatory bowel disease among others. Autoinflammatory disorders are defined by repeating episodes or persistent fever, rash, serositis, lymphadenopathy, arthritis and increased acute phase reactants, and thus may mimic infections clinically. Most monogenic autoinflammatory syndromes present in childhood. However, because of their infrequency, diverse and nonspecific presentation, and the relatively new genetic recognition, diagnosis is usually delayed. In this article, which is Part 1 of a two-part series, the authors update monogenic autoinflammatory diseases in children with special emphasis on imaging features that may help establish the correct diagnosis.

Validation of a diagnostic score for the diagnosis of autoinflammatory diseases in adults

Most autoinflammatory disorders typically come out in the pediatric population, although a limited number of patients may experience disease onset during adulthood. To date, a late disease onset has been described only in familial Mediterranean fever, caused by mutations in the MEFV gene, and in tumor necrosis factor receptor-associated periodic syndrome, caused by mutations in the TNFRSF1A gene. The relative rarity and lack of information on adult-onset autoinflammatory diseases make it likely that mutations will be found in an even smaller percentage of cases. With the aim of improving the genetic diagnosis in adults with suspected autoinflammatory disorders, we recently identified a set of variables related to the probability of detecting gene mutations in MEFV and TNFRSF1A and, in addition, we have also proposed a diagnostic score for identifying those patients at high risk of carrying mutations in these genes. In the present study we evaluated the preliminary score sensitivity and specificity on a wider number of patients in order to validate the goodness of fit of the model. Two hundred and nineteen consecutive patients with a clinical history of periodic fever attacks were screened for mutations in MEFV and TNFRSF1A genes; detailed information about family/personal history and clinical manifestations were also collected. For the validation of the score we considered data both from the 110 patients used to build the preliminary diagnostic score and from the additional 219 patients enrolled in the present study, for a total number of 329 patients. Early age at disease onset, positive family history for recurrent fever episodes, thoracic pain, abdominal pain and skin rash, which are the variables that had previously been shown to be significantly associated with a positive genetic test result (12), were used for validation. On univariate analysis the associations with a positive genetic test were: age at onset (odds ratio [OR] 0.43, p=0.003), positive family history for recurrent fever episodes (OR 5.81, p<0.001), thoracic pain (OR 3.17, p<0.001), abdominal pain (OR 3.80, p<0.001) and skin rash (OR 1.58, p=0.103). The diagnostic score was calculated using the linear combination of the estimated coefficients of the logistic multivariate model (cut-off equals to 0.24) revealing good sensitivity (0.778) and good specificity (0.718). In conclusion, our score may serve in the diagnostic evaluation of adult patients presenting with recurrent fever episodes suspected of having an autoinflammatory disorder, helping identify the few subjects among them who may be carriers of mutations in MEFV and TNFRSF1A genes.

Development and preliminary validation of a diagnostic score for identifying patients affected with adult-onset autoinflammatory disorders

To date, the rate of detection of autoinflammatory gene mutations in patients suspected of having an autoinflammatory disorder is very low. However, most of these data refer to pediatric populations. The relative rarity and lack of information on adult-onset autoinflammatory diseases make it likely that mutations will be found in an even smaller percentage of cases. Our aim was to develop and validate a set of variables for predicting the risk that a given adult patient presenting with recurrent fever episodes carries mutations in the MEFV or TNFRSF1A genes, in order to increase the probability of obtaining positive results on genetic testing. One hundred and ten consecutive patients with a clinical history of periodic fever attacks were screened for mutations in the TNFRSF1A and the MEFV genes. The mean age at disease onset was 27.85 years. Detailed information about each patient?s family history, personal history, and clinical manifestations were retrospectively collected. A diagnostic score was constructed based on univariate and multivariate analysis in a randomly-selected dataset (training set; n=40). The score was validated on an independent set of the remaining patients (validation set; n=70). Age at onset (odds ratio 0.958, P =0.050), positive family history of recurrent fever episodes (OR 5.738, P = 0.006 ), thoracic pain (OR 7.390, P = 0.002), abdominal pain (OR 2.853, P = 0.038) and skin involvement (OR 8.241, P = 0.003) were independently correlated with a positive genetic test result. A diagnostic score was calculated using the linear combination of the estimated coefficients of the logistic model (cut off equal to 0.24) revealing high sensitivity (0.94), high specificity (0.94) and high accuracy (0.94). We have identified variables that appear to be strongly related to the probability of detecting gene mutations in MEF and TNFRSF1A in adults, thus improving the evaluation of patients with suspected autoinflammatory disorders.

[TRAPS: clinical significance of genotype. A report of two cases]

INTRODUCTION

Tumor necrosis factor receptor associated periodic fever syndrome (TRAPS) is defined as recurrent attacks of generalized inflammation for which no infectious or auto-immune cause can be identified; it is caused by dominantly inherited mutations in the gene encoding the first TNF receptor. We report two additional cases of patients with TRAPS, suggesting that mutation pattern of TNFRSF 1A gene may influence the TRAPS phenotype.

CASE REPORTS

The first patient, with a C30S mutation, exhibited severe digestive clinical manifestations; because the patient required high-dose corticosteroids regimen to improve TRAPS manifestations, he was further given successfully etanercept. The second patient, with a R92Q mutation of TNFRSF 1A gene, presented with moderate symptoms; TRAPS outcome was favourable after corticosteroid therapy initiation.

CONCLUSION

Therefore, R92Q may be associated with a mild disease phenotype. On the other hand, C30S mutation appears to be associated with a severe phenotype, leading to an increased risk of amyloidosis. These findings suggest that these latter patients may require a closer follow-up.

Typical and severe tumor necrosis factor receptor-associated periodic syndrome in the absence of mutations in the TNFRSF1A gene: a case series

Tumor necrosis factor receptor-1-associated periodic syndrome (TRAPS) is the most common autosomal dominant autoinflammatory disorder and is caused by mutations in the TNFRSF1A gene encoding the 55-kDa receptor for tumor necrosis factor (TNF)-α. TRAPS is characterized by recurrent attacks of fever, typically lasting from 1 to 3 weeks. In addition to fever, common clinical features include periorbital edema, a migratory erythematous plaque simulating erysipela with underlying myalgia, and arthralgia or arthritis. Serosal membrane inflammation is also a common feature, usually in the form of polyserositis. To date, at least 40 different TNFRSF1A mutations have been identified, but few patients with symptoms highly suggestive of TRAPS with no mutations in the TNFRSF1A gene have recently been described, thus suggesting that not all mutations are yet known or that alternative mechanisms might be involved in the pathogenesis of the disease. We report on three such patients here.

A novel Y331X nonsense mutation in TNFRSF1A gene in two unrelated Turkish families with periodic fever syndrome

The autoinflammatory disorders differ in severity, as well as age of onset, duration, and manifestations, but they all share some common features: recurring fever peaks, inflammation of serosal membranes, musculoskeletal involvement, varying types of skin rash, amyloidosis as a sequel of the disease. TRAPS is very rare in Turkish population and we present two unrelated Turkish children with similar clinical phenotypes and laboratory findings related with autoinflammatory disorders and with novel p. Y331X mutation in TNFRSF1A gene. Both of the patients were male and they had recurrent fever without abdominal pain and arthralgia. Full cDNA and exon-intron binding regions of TNFRSF1A, MEFV, MVK, CIAS1 genes were analysed by direct DNA sequencing methods in order to differentiate TRAPS, FMF, HIDS, CINCA/MWS/FCAS respectively. We screened ten exons of TNFRSF1A gene, and detected a heterozygous c.1080C>G nucleotide substitution in exon 10 in both of the unrelated patients, resulting p.Y360X nonsense (protein truncated) mutation. According to classical TNFRSF1A gene nomenclature and the agreement of 30th amino acid as the first one, it is accepted as p.Y331X. It was interesting to determine same mutations in fathers of two patients. In one of the cases, E148Q heterozygous mutation, which is one of the disease-causing mutations of MEFV gene, was detected. No nucleotide substitution was identified in exon and exon-intron splicing regions encoding 396 amino acid of MVK gene in both of the patients. In CIAS1 gene, two different nucleotide substitutions resulting synonymous amino acid mutation were detected in exon 3: c.[732G>A] and c.[786A>G] nucleotide substitutions and compatible p.A242A (according to c.DNA p.A244A) and p.R260R (according to c.DNA p.R262R) synonymous amino acid mutations. These nucleotide substitutions were also detected in parents and were reported to be normal variations in Turkish population. In conclusion, in Turkish patients, with dominantly inherited recurrent fever, TRAPS is a diagnosis worthy of attention and novel mutations have to be reported with phenotype associations.

TNF receptor-associated periodic syndrome (TRAPS): description of a novel TNFRSF1A mutation and response to etanercept

TRAPS is the most common of the autosomal dominant periodic fever syndromes. It is caused by mutations in the TNFRSF1A gene, which encodes for the type 1 TNF-receptor (TNFR1). We describe here a Brazilian patient with TRAPS associated to a novel TNFRSF1A de novo mutation and the response to anti-TNF therapy. The patient is a 9-year-old girl with recurrent fevers since the age of 3 years, usually lasting 3 to 7 days, and recurring every other week. These episodes are associated with mild abdominal pain, nausea, vomiting and generalized myalgia. Recurrent conjunctivitis and erysipela-like skin lesions in the lower limbs also occur. Laboratory studies show persistent normocytic normochromic anemia, thrombocytosis, elevated erythrocyte sedimentation rate and C-reactive protein. IgD levels are normal. Mutational screening of TNFRSF1A revealed the association of a novel C30F mutation with the common R92Q low-penetrance mutation. The R92Q mutation is seen in 5% of the general population and is associated with an atypical inflammatory phenotype. The patient had a very good response to etanercept, with cessation of fever and normalization of inflammatory markers. Our report expands the spectrum of TNFRSF1A mutations associated with TRAPS, adding further evidence for possible additive effects of a low-penetration R92Q and cysteine residue mutations, and confirms etanercept as an efficacious treatment alternative.

[The "self-inflammatory syndrome"]

The "self-inflammatory syndrome" gathers diseases all characterized by a recurrent inflammatory syndrome with fever, in the absence of infection or neoplasia. It is based on a genetic support characterized by mutations in genes implied in the inflammatory response and in the activation of the cytokine network. The diseases associated with this syndrome are familial Mediterranean fever (FMF), TRAPS (tumor necrosis factor receptor super family 1 A-associated periodic syndrome), familial cold urticaria, the Muckle-Wells syndrome, the hyper IgD syndrome and CINCA. The clinical symptoms of all these diseases include in the auto-inflammatory syndrome are quite similar: recurrent attacks, with fever, articular, abdominal, cutaneous symptoms, and an inflammatory syndrome.

Clinical significance of P46L and R92Q substitutions in the tumour necrosis factor superfamily 1A gene

OBJECTIVE

Tumour necrosis factor receptor-associated periodic syndrome (TRAPS) has been associated with several mutations in the TNF receptor super family 1A (TNFRSF1A), including most cysteine substitutions. However, the nature of two substitutions, P46L and R92Q, remains a topic of discussion. The aim of this study was to assess the actual role of these two sequence variations in a series of patients with TRAPS.

METHODS

The main clinical data of 89 patients with TRAPS have been prospectively registered on a standard form. 84 patients or members of families with recurrent episodes of inflammatory symptoms spanning a period of more than 6 months and harbouring a TNFRSF1A mutation were studied. Clinical data have been analysed according to the nature of the mutation-P46L, R92Q or others.

RESULTS

P46L is often seen in patients from Maghreb and is associated with a mild phenotype. P46L appears as a polymorphism with a non-specific role in inflammation. R92Q is associated with a variable phenotype and presents as a low-penetrance mutation. Interpreting these results will require a comparison with clinical signs and genetic background.

TNF-receptor-associated periodic syndrome (TRAPS): an autosomal dominant multisystem disorder

The TNF-receptor-associated periodic syndrome (TRAPS) is an autosomal dominant auto-inflammatory disorder, characterized by recurrent febrile attacks and localized inflammation. TRAPS is caused by mutations in the gene encoding the TNF Receptor Super Family 1A (TNFRSF1A) on chromosome 12p13. However, the incomplete penetrance and genetic heterogeneity have been reported in this syndrome. Although the ethnic diversity and clinical heterogeneity may propose the role of other genes in the pathogenesis of TRAPS, some low-penetrance TNFRSF1A variants contribute to atypical inflammatory responses in other autoimmune diseases. Furthermore, molecular studies on TRAPS and other auto-inflammatory disorders could be suggested to identify additional genes coding the molecules in the TNF signalling process.

Approach to genetic analysis in the diagnosis of hereditary autoinflammatory syndromes

OBJECTIVE

Hereditary autoinflammatory syndromes are characterized by recurrent episodes of fever and inflammation. Seven subtypes have been described, caused by mutations in four different genes. Apart from a common phenotype of lifelong recurrent inflammatory attacks, all subtypes have distinct features and specific therapeutic options, which emphasizes the need for a specific diagnosis in each case. Our aim was to examine whether genetic screening would allow classification of previously unclassified patients, and whether individual patients suffering from an autoinflammatory syndrome carry additional mutations in one of the other autoinflammatory genes.

METHODS

We included 60 patients with an unclassified autoinflammatory syndrome, 87 patients diagnosed with either hyper-IgD syndrome, familial Mediterranean fever (FMF) or tumour necrosis factor (TNF)-receptor-associated periodic syndrome and 50 healthy controls. Deoxyribonucleic acid samples were screened for the most prevalent mutations in the MEFV, TNFRSF1A, MVK and CIAS1 genes.

RESULTS

We found only one possible diagnosis of FMF in the 60 previously unclassified patients. Two low-penetrance mutations were found in equal numbers in the groups of patients and controls.

CONCLUSIONS

Screening of highly prevalent mutations in known genes involved in these disorders does not yield additional relevant information. Differential diagnosis of hereditary autoinflammatory syndromes can be made by thorough clinical examination followed by targeted genetic analysis of the one or two most likely syndromes. High-prevalence low-penetrant mutations from autoinflammatory genes do not occur more frequently in patients with hereditary autoinflammatory syndromes compared with the general population.

Unexpected high frequency of P46L TNFRSF1A allele in sub-Saharan West African populations

TNF receptor-associated periodic syndrome (TRAPS) is an autosomal dominant disorder characterized by recurrent attacks of fever and serositis. To date, more than 30 mutations have been reported in TNFRSF1A, the responsible gene. In Caucasian populations, the P46L (c.224C>T) TNFRSF1A sequence variation is considered as a low-penetrance mutation because its allele frequency is similar in patients and controls ( approximately 1%). Whereas the spectrum of TNFRSF1A gene mutations has been well established in Caucasian and several Mediterranean populations, it remains unknown in sub-Saharan African populations. In this study, we found an unexpected high P46L allele frequency ( approximately 10%) in two groups from West Africa - a group of 145 patients with sickle cell anaemia and a group of 349 healthy controls. These data suggest that the P46L variant is rather a polymorphism than a TRAPS causative mutation. We propose that the P46L high frequency in West African populations could be explained by some biological advantage conferred to carriers.

Etanercept plus colchicine treatment in a child with tumour necrosis factor receptor-associated periodic syndrome abolishes auto-inflammatory episodes without normalising the subclinical acute phase response

We investigated the cause of hereditary periodic fever syndrome in a Spanish child with recurrent long episodes of fever, migratory skin rash, myalgia, arthralgia, conjunctivitis and abdominal pain. Infectious and autoimmune causes were ruled out. No familial history was reported. Analysis of the tumour necrosis factor receptor superfamily 1A (TNFRSF1A) gene identified a missense mutation (G36E) on exon 3. The absence of this variant in the patient's parents and in controls identified it as a de novo disease-associated mutation. Clinical symptoms disappeared with administration of etanercept; however, levels of acute-phase reactants remained increased and could not be stabilised by the addition of colchicine. We believe that this patient gained some symptomatic relief with etanercept therapy, although not enough to completely avoid the risk of amyloidosis. Thus it is debatable whether etanercept alone or combined with other drugs, is the treatment of choice for patients with tumour necrosis factor receptor-associated periodic syndrome.

CONCLUSION

Since there is variability in treatment responses among different patients with tumour necrosis factor receptor-associated periodic syndrome, we suggest that a systematic evaluation of acute-phase reactants, especially SAA-1, could be useful in maintaining or modifying a given therapeutic approach in these patients.

In silico prediction of the deleterious effect of a mutation: proceed with caution in clinical genetics

When a sequence variation is found in a candidate gene for a disease, it is important to establish whether this change is neutral or responsible for the observed disorders in a patient. To answer this question, in the absence of further experimental investigations, several simulation programs have been proposed to predict whether a nonsynonymous single-nucleotide polymorphism is likely to have or not have a deleterious effect on the phenotype. In this work, we tested two such programs, PolyPhen and SIFT, using two kinds of targets. The first ones concerned the products of the hemoglobin and glucose-6-phosphate dehydrogenase genes, which are abundantly documented. The second concerned two systems for which much less information is available: (a) the TNFRSF1A gene, implicated in tumor necrosis factor receptor-associated periodic syndrome, and (b) the MEFV gene, which is believed to be involved in familial Mediterranean fever. Our data suggest that, from a practical point of view, these programs should not be used to decide, in the absence of other tests or arguments, whether the sequence variation found in a patient is or is not responsible for the disease. The consequence of an erroneous prediction may be disastrous in the perspective of genetic counseling.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS): definition, semiology, prognosis, pathogenesis, treatment, and place relative to other periodic joint diseases

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is an autosomal dominant inherited condition of periodic fever and pain. Most patients are of northern European descent. The attacks manifest as fever and pain in the joints, abdomen, muscles, skin, or eyes, with variations across patients. An acute-phase response occurs during the attacks. Patients with TRAPS are at risk for AA amyloidosis, the most common targets being the kidneys and liver. Soluble TNFRSF1A is usually low between the attacks and may be normal during the attacks, when TNF levels are high. TNFRSF1A is found in abnormally high numbers on leukocyte cell membranes. TRAPS is the first condition for which naturally occurring mutations in a TNF receptor were found; the mutations affect the soluble TNFRSF1A gene in the 12p13 region. In some patients, the pathogenesis involves defective TNFRSF1A shedding from cell membranes in response to a given stimulus. Thus, TRAPS is a model for a novel pathogenic concept characterized by failure to shed a cytokine receptor. This review compares TRAPS to other inherited periodic febrile conditions, namely, familial Mediterranean fever, Muckle-Wells syndrome, cold urticaria, and hyper-IgD syndrome. The place of TRAPS relative to other intermittent systemic joint diseases is discussed. Colchicine neither relieves nor prevents the attacks, whereas oral glucocorticoid therapy is effective when used in dosages greater than 20 mg/day. The pathogenic hypothesis involving defective TNFRSF1A shedding suggests that medications targeting TNF may be effective in TRAPS.

Inherited disorders of cytokines

PURPOSE OF REVIEW

Cytokines are soluble mediators involved in the development or function of the immune system. This paper reviews the literature on childhood-onset inherited disorders associated with impaired cytokine-mediated immunity.

RECENT FINDINGS

Cytokine-mediated immunity defects can be classified into seven different groups: defects in the interleukin (IL)-7 receptor (IL7RA), in the common cytokine receptor gamma chain (gammac) of the IL-2, -4, -7, -15, and -21, and in Jak3 (JAK3) downstream of the gamma chain; mutation in the IL-2 receptor alpha (IL-2RA) and defective expression of the IL-2Rbeta chain; mutations in the gene encoding for a chemokine receptor, CXCR4; mutations in five genes involved in the IL-12/23-interferon-gamma axis (IL12B, IL12RB1, IFNGR1, IFNGR2, STAT1); mutations in three genes involved in the nuclear factor-kappaB signaling pathway (IRAK4, NEMO, IkappaBA); mutations in the tumor necrosis factor receptor signaling pathway (TNFRSF1A); and mutations in the transforming growth factor-1 gene (TGFB1).

SUMMARY

Genetic cytokine-mediated immunity defects are associated with a highly heterogeneous group of clinical features, ranging from susceptibility to infections to developmental defects. This heterogeneity highlights the diversity and pleiotropy of cytokines. It is likely that many more cytokine defects and their responsive pathways will be discovered in the coming years, expanding further the heterogeneity associated with this group of childhood-onset illnesses.

Mutant forms of tumour necrosis factor receptor I that occur in TNF-receptor-associated periodic syndrome retain signalling functions but show abnormal behaviour

Tumour necrosis factor (TNF)-receptor-associated periodic syndrome (TRAPS) is a hereditary autoinflammatory disorder involving autosomal-dominant missense mutations in TNF receptor superfamily 1A (TNFRSF1A) ectodomains. To elucidate the molecular effects of TRAPS-related mutations, we transfected HEK-293 cells to produce lines stably expressing high levels of either wild-type (WT) or single mutant recombinant forms of TNFRSF1A. Mutants with single amino acid substitutions in the first cysteine-rich domain (CRD1) were produced both as full-length receptor proteins and as truncated forms lacking the cytoplasmic signalling domain (deltasig). High-level expression of either WT or mutant full-length TNFRSF1A spontaneously induced apoptosis and interleukin-8 production, indicating that the mutations in CRD1 did not abrogate signalling. Consistent with this, WT and mutant full-length TNFRSF1A formed cytoplasmic aggregates that co-localized with ubiquitin and chaperones, and with the signal transducer TRADD, but not with the inhibitor, silencer of death domain (SODD). Furthermore, as expected, WT and mutant deltasig forms of TNFRSF1A did not induce apoptosis or interleukin-8 production. However, whereas the WT full-length TNFRSF1A was expressed both in the cytoplasm and on the cell surface, the mutant receptors showed strong cytoplasmic expression but reduced cell-surface expression. The WT and mutant deltasig forms of TNFRSF1A were all expressed at the cell surface, but a proportion of the mutant receptors were also retained in the cytoplasm and co-localized with BiP. Furthermore, the mutant forms of surface-expressed deltasig TNFRSF1A were defective in binding TNF-alpha. We conclude that TRAPS-related CRD1 mutants of TNFRSF1A possess signalling properties associated with the cytoplasmic death domain, but other behavioural features of the mutant receptors are abnormal, including intracellular trafficking and TNF binding.

Fièvres intermittentes héréditaires

Other than familial mediterranean fever: Four hereditary diseases presenting in the form of intermittent inflammatory flares are now recognized and have been characterised clinically and genetically. At the head of this group is Familial Mediterranean Fever (FMF), which affects thousands of patients originating from the Mediterranean area. However the familial Mediterranean Fever is no longer the only recurrent hereditary inflammatory disease. Three other entities have now been clearly defined: intermittent fever secondary to mutations in the type 1A Tumour Necrosis Factor receptor (TNF), of dominant autosomic genetic transmission, the hyperimmunoglobulinemia D syndrome and an entity regrouping the Muckle Wells syndrome, familial cold-induced urticaria, and the Chronic Infantile Neurological Cutaneous and Articular (CINCA) syndrome.

IN PRACTICE

Because they require specific management and treatment, precise diagnosis of these entities is crucial.

[Tumor necrosis factor receptor superfamily 1A-associated periodic syndrome (TRAPS)]

PURPOSE

Tumor necrosis factor receptor superfamily 1A associated periodic syndrome (TRAPS) belongs to the group of hereditary fever syndromes, also called hereditary auto-inflammatory syndromes.

CURRENT KNOWLEDGE AND KEY POINTS

The diagnosis of TRAPS should be evoked in presence of the following clinical signs, whatever the population of the affected patients. TRAPS acute inflammatory access, of 1 to 3 weeks' duration, is characterised by the presence of fever, abdominal pain, myalgias, various types of skin rash including erysepela-like erythema. Long term inflammatory response can lead to AA amyloidosis. Genetic testing will confirm the diagnosis when showing a mutation in the extracellular part of the TNFRSF1A receptor. Therapeutic management of TRAPS is not definitely established. Daily colchicine does not seem to prevent efficiently inflammatory attacks. Corticosteroids, in contrast can attenuate the intensity and diminish the duration of attacks.

FUTURE PROSPECTS AND PROJECTS

The value of biological agents that inhibits TNF action is not yet completely determined in TRAPS. Mechanisms of the disease are not yet elucidated. In some families with specific mutations, a relative soluble TNF receptor deficiency has been found in the plasma. However this mechanism does not account for what is observed in other kindreds.

ATNFR1genotype with a protective role in familial rheumatoid arthritis

OBJECTIVE

Results of genome scans in rheumatoid arthritis (RA) have suggested that the tumor necrosis factor receptor I (TNFRI) and TNFRII loci (TNFR1 and TNFR2) are susceptibility loci. A TNFR2 polymorphism was found to be associated with familial RA. TNFR1 is mutated in TNFR-associated periodic syndrome (TRAPS). We undertook this study to test the TNFR1 exonic polymorphism closest to the TRAPS mutations site (+36 A/G) for association with RA.

METHODS

DNA samples were available from two groups of the French Caucasian population: 1) 100 families with 1 RA patient and both parents and 2) 86 RA index patients from families with at least 2 siblings with RA (affected sibpairs [ASPs]). The +36 A/G polymorphism of TNFR1 was genotyped by polymerase chain reaction-restriction fragment length polymorphism. The analysis was performed using the transmission disequilibrium test, the genotype relative risk, and a linkage-based test previously described.

RESULTS

A negative association between RA and the +36 A/A genotype, suggested in the first sample (P = 0.084), was demonstrated in the second (ASP RA) sample (odds ratio [OR] 0.465; P = 0.012) and confirmed by the linkage-based test (OR 0.17; P = 0.008). The protective genotype, present in 41% of controls, was less frequent in RA patients: 33% in the first sample, 24% in the ASP RA sample, and 11% in the linkage-derived subgroup. Distribution of both TNFR2 196 R/R and TNFR1 +36 A/A genotypes in the ASP RA sample showed that both suspected genotypes were exclusive.

CONCLUSION

We found evidence for an association between RA and a TNFR1 protective genotype, restricted to familial RA. Distribution of the TNFR2 196 R/R and TNFR1 +36 A/A genotypes in familial RA could suggest an interaction between TNFR1 and TNFR2 in the genetic susceptibility for RA.

Identifying Mutations in Autoinflammatory Diseases

Autoinflammatory diseases are defined as illnesses caused by primary dysfunction of the innate immune system. This new concept includes a broad number of disorders, but the spotlight has been focused for the past two years on periodic fevers (familial Mediterranean fever [FMF]; mevalonate kinase deficiency [MVK]; tumor necrosis factor [TNF] receptor-associated periodic syndrome [TRAPS]; cryopyrin-associated periodic syndrome [CAPS]), Crohn's disease and Blau syndrome, thanks to the recent understanding of their molecular basis. Indeed, until recently, these conditions were defined only by phenotypical features, the main ones being recurrent attacks of fever, abdominal pain, arthritis, and cutaneous signs, which sometimes overlap, obscuring diagnosis. The search for distinguishing signs such as periorbital edema in TRAPS, and the use of specific functional tests where available, are valuable. Needless to say, molecular screening of the causative genes has dramatically improved patient quality-of-life by providing early and accurate diagnosis, subsequently allowing for the appropriate treatment. Some patients, however, remain hard to manage despite the advent of new genetic tests, and/or due to the lack of effective treatment. The original clinical link between the aforementioned diseases can now be confirmed by a molecular one, following the exciting discovery that most of the altered proteins are related to the death domain fold (DDF) superfamily involved in inflammation and apoptosis. These molecules mediate the regulation of nuclear factor-kappa B (NF-kappa B) activation, cell apoptosis, and interleukin-1 beta secretion through cross-regulated and, sometimes, common signaling pathways. Knowledge of the defective step in autoinflammation has already led to the elucidation of the mechanisms of action of existing drugs and may allow the development of new therapies.

Shedding of mutant tumor necrosis factor receptor superfamily 1A associated with tumor necrosis factor receptor-associated periodic syndrome: Differences between cell types

OBJECTIVE

To investigate the effect of mutations in tumor necrosis factor receptor superfamily 1A (TNFRSF1A) on the ability of the receptors to be cleaved from the cell surface upon stimulation. The mutations we studied are associated with clinically distinct forms of TNF receptor-associated periodic syndrome (TRAPS). We also investigated different cell types within the same form of TRAPS.

METHODS

The shedding of TNFRSF1A in response to stimulation with phorbol myristate acetate was assessed in leukocytes and dermal fibroblasts from patients with C33Y TRAPS, and in HEK 293 cell lines stably transfected with constructs containing wild-type TNFRSF1A and/or TNFRSF1A mutants identified in TRAPS patients.

RESULTS

The shedding of TNFRSF1A differed between cell types within the same form of TRAPS. In particular, dermal fibroblasts, but not leukocytes, from C33Y TRAPS patients demonstrated reduced shedding of TNFRSF1A. Shedding of both wild-type and mutant TNFRSF1A from the transfected HEK 293 cells showed minor differences, but was in all cases induced to a substantial extent.

CONCLUSION

Differences in TNFRSF1A shedding are not purely a function of the TNFRSF1A structure, but are also influenced by other features of genetic makeup and/or cellular differentiation. It is unlikely that a defect in TNFRSF1A shedding per se can fully explain the clinical features that are common to TRAPS patients with different TNFRSF1A mutations.

Heterogeneity among patients with tumor necrosis factor receptor-associated periodic syndrome phenotypes

OBJECTIVE

To investigate the prevalence of tumor necrosis factor receptor-associated periodic syndrome (TRAPS) among outpatients presenting with recurrent fevers and clinical features consistent with TRAPS.

METHODS

Mutational screening was performed in affected members of 18 families in which multiple members had symptoms compatible with TRAPS and in 176 consecutive subjects with sporadic (nonfamilial) "TRAPS-like" symptoms. Plasma concentrations of soluble tumor necrosis factor receptor superfamily 1A (sTNFRSF1A) were measured, and fluorescence-activated cell sorter analysis was used to measure TNFRSF1A shedding from monocytes.

RESULTS

Eight novel and 3 previously reported TNFRSF1A missense mutations were identified, including an amino acid deletion (Delta D42) in a Northern Irish family and a C70S mutation in a Japanese family, both reported for the first time. Only 3 TNFRSF1A variants were found in patients with sporadic TRAPS (4 of 176 patients). Evidence for nonallelic heterogeneity in TRAPS-like conditions was found: 3 members of the "prototype familial Hibernian fever" family did not possess C33Y, present in 9 other affected members. Plasma sTNFRSF1A levels were low in TRAPS patients in whom renal amyloidosis had not developed, but also in mutation-negative symptomatic subjects in 4 families, and in 14 patients (8%) with sporadic TRAPS. Reduced shedding of TNFRSF1A from monocytes was demonstrated in vitro in patients with the T50M and T50K variants, but not in those with other variants.

CONCLUSION

The presence of TNFRSF1A shedding defects and low sTNFRSF1A levels in 3 families without a TNFRSF1A mutation indicates that the genetic basis among patients with "TRAPS-like" features is heterogeneous. TNFRSF1A mutations are not commonly associated with nonfamilial recurrent fevers of unknown etiology.

[TNF receptor-associated periodic syndrome (TRAPS): clinical aspects and physiopathology of a rare familial disease]

Hereditary periodic fever syndromes are defined as recurrent attacks of generalized inflammation for which no infectious or auto-immune cause can be identified. Minimal clinical variations, a unique biochemical-specific abnormality and the mode of genetic inheritance distinguish the four main diseases: familial Mediterranean fever, hyper-immunoglobulinemia D, TNF-receptor-associated periodic syndrome (TRAPS) and Muckle Wells syndrome. It presents with prolonged attacks of fever and severe localized inflammation. TRAPS is caused by dominantly inherited mutations in the gene encoding the first TNF receptor, which result in decreased serum levels of soluble TNF-receptor leading to inflammation due to unopposed TNF-alpha action. Corticosteroid treatment is not completely effective in most TRAPS patients. Preliminary experiences with recombinant TNF-receptor analogues in the treatment appear be promising.

Genetic clues to understanding periodic fevers, and possible therapies

Significant breakthroughs in our understanding of the molecular basis of the inflammatory response have been achieved in the past five years, with the successive identification of the genetic basis of all known hereditary periodic-fever syndromes. Impaired cytokine recognition and defective signalling molecules have been implicated in the inception of recurrent attacks of fever with acute-phase protein response. Disorders of interleukin-1 processing and of regulation of nuclear factor kappaB transcription factor, and possibly defective apoptosis, might be involved in the pathogenesis of all but one of these disorders. Mutations in genes of both the pyrin and tumour-necrosis-factor-receptor superfamilies are postulated to lead to the survival of leukocytes that would ordinarily undergo apoptosis, and ultimately to a prolonged inflammatory response. Improved therapies have reduced the incidence of systemic amyloidosis, but this complication remains the most frequent cause of death.

Genetic and environmental risk factors for idiopathic inflammatory myopathies

Although the studies discussed are beginning to reveal a number of genetic and possible environmental risk factors for myositis, further investigations are needed to fully understand and classify these syndromes. The difficulties in this process include small numbers of subjects with varying disease phenotypes available for study, polygenic risk factors for which it remains unclear which are primary and which are secondary or linked genes, and the lack of validated environmental exposure assessment tools. New technologies and international collaborative approaches, however, may overcome some of these difficulties and allow us to identify genetic and environmental risk factors, as well as the critical gene-environment interactions in the IIM and its subgroups. Nonetheless, our understanding of these diseases is still in the early stages. Although we have learned a great deal about these disorders through detailed investigations over the last several decades, we have even further to go to understand the environmental triggers and genetic susceptibilities for the myositis syndromes.

Clarifying the boundaries between the inflammatory and dystrophic myopathies: insights from molecular diagnostics and microarrays

Clinical and histopathologic overlaps between the muscular dystrophies and inflammatory myopathies are being increasingly recognized. Most patients with a muscular dystrophy show improvement with prednisone treatment, although they will not be cured; many patients with idiopathic inflammatory myopathies are cured. Dysferlin-deficiency was recently recognized as a cause of late-onset dystrophy with substantial inflammation in muscle. Corticosteroid usage by these patients may result in nonrecoverable loss of strength. Therefore, it is important to rule out dysferlin-deficiency before initiating a course of corticosteroids. Newly emerging, genome-wide transcriptional profiling technology allows the identification of the interacting pathways that are active in the muscle of patients with inflammatory myopathies or dystrophies. There are several, complex molecular pathways; however, the comparison of expression profiles in patients with different muscle disorders permits the delineation of disease-specific patterns. It is hoped that novel approaches for treating the inflammatory myopathies and dystrophies can be derived from intimate knowledge of the pathways involved in each disease, and the key molecules that provide cross-talk between pathways.

The TNF receptor-associated periodic syndrome (TRAPS): emerging concepts of an autoinflammatory disorder

The present report describes and expands the clinical and genetic spectrum of the autoinflammatory disorder, tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS). A total of 20 mutations have been identified since our initial discovery of 6 missense mutations in TNF receptor super family 1A (TNFRSF1A) in 1999. Eighteen of the mutations result in amino acid substitutions within the first 2 cysteine-rich domains (CRDs) of the extracellular portion of the receptor. A single splicing mutation also affects the first CRD by causing the insertion of 4 amino acids. Haplotype analysis of the most commonly occurring and ethnically heterogeneous mutation, R92Q, demonstrates an ancient founder; however, analysis of the T50M mutation, another commonly occurring mutation in Irish and Scottish families, does not, suggesting that T50M is a recurring mutation. Mutations that result in cysteine substitutions demonstrate a higher penetrance of the clinical phenotype (93% versus 82% for noncysteine residue substitutions), and also increase the probability of developing life-threatening amyloidosis (24% versus 2% for noncysteine residue substitutions). Retrospective and prospective evaluation of more than 50 patients, representing 10 of the 20 known mutations, allows us to expand and better define the clinical spectrum of TRAPS. Recurrent episodes of fever, myalgia, rash, abdominal pain, and conjunctivitis that often last longer than 5 days are the most characteristic clinical features of TRAPS. Defective shedding of TNFRSF1A can only partially explain the pathophysiologic mechanism of TRAPS, since some mutations have normal shedding. Consequently, other mechanisms may be mediating the observed phenotype. We are currently investigating other possible mechanisms using stable and transiently transfected cell systems in vitro, as well as developing a knockin mouse model. Preliminary data suggest that etanercept may be effective in decreasing the severity, duration, and frequency of symptoms in TRAPS patients. Additionally, it provides a viable therapeutic alternative to glucocorticoid therapy, which has numerous serious, long-term adverse effects. Two clinical trials are being conducted to evaluate the efficacy of etanercept in decreasing the frequency and severity of symptoms in TRAPS. Lastly, we have summarized data that R92Q and P46L, and probably as yet undiscovered substitutions, represent very low penetrance mutations that may play a much larger role in more broadly defined inflammatory diseases such as rheumatoid arthritis. Our laboratories are currently undertaking both clinical and basic research studies to define the role of these mutations in more common inflammatory diseases.

Monocytic fasciitis: a newly recognized clinical feature of tumor necrosis factor receptor dysfunction

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is a dominantly inherited autoinflammatory syndrome that results from mutations in TNFRSF1A, the gene that encodes the 55-kd tumor necrosis factor receptor. Clinically, patients present with recurrent episodes of fever in conjunction with localized inflammation at various sites. Myalgia is one of the most characteristic features of this syndrome and is frequently associated with an overlying erythematous, macular rash that, together with the myalgia, displays centrifugal migration. This has previously been believed to occur as a result of myositis. We describe herein the case of a 60-year-old man with TRAPS, in whom magnetic resonance imaging of the left thigh demonstrated edematous changes in the muscle compartments and surrounding soft tissues. A full-thickness wedge biopsy was performed, and hematoxylin and eosin staining and immunohistochemistry analysis of the specimen demonstrated normal myofibrils but a severely destructive monocytic fasciitis. These results suggest that the myalgia experienced by individuals with TRAPS is due to a monocytic fasciitis and not to myositis.

The enlarging clinical, genetic, and population spectrum of tumor necrosis factor receptor-associated periodic syndrome

OBJECTIVE

To characterize the frequency, clinical signs, and genotypic features of tumor necrosis factor receptor-associated periodic syndrome (TRAPS) in a series of 394 patients of various ethnic origins who have recurrent inflammatory syndromes.

METHODS

Sequencing of the coding region of the TNFRSF1A gene was performed in 128 patients in whom there was a high suspicion of TRAPS, and denatured high-performance liquid chromatography was used to systematically screen for TNFRSF1A in 266 patients with recurrent inflammatory syndrome and no or only 1 Mediterranean fever gene (MEFV) mutation.

RESULTS

TNFRSF1A mutations were found in 28 (7.1%) of 394 unrelated patients. Nine (32%) of the 28 patients had a family history of recurrent inflammatory syndromes. In 13 patients, the length of the attack of inflammation was fewer than 5 days. Three of the mutations (Y20H, L67P, and C96Y) were novel. Two mutations, R92Q and (mainly) P46L, found in 12 and 10 patients, respectively, had lower penetrance compared with other mutations. TNFRSF1A mutations were found in patients of various ethnic origins, including those at risk for familial Mediterranean fever (FMF): Armenians, Sephardic Jews, and especially Arabs from Maghreb. Only 3 (10.7%) of the 28 patients had amyloidosis.

CONCLUSION

TRAPS is an underdiagnosed cause of recurrent inflammatory syndrome. Its presence in the population of persons of Mediterranean ancestry and the short duration of the attacks of inflammation can lead to a fallacious diagnosis of FMF. Because an accurate diagnosis in patients with recurrent inflammatory syndromes is crucial for proper clinical management and treatment, genetic screening for TNFRSF1A is warranted.

A novel mutation in the third extracellular domain of the tumor necrosis factor receptor 1 in a Finnish family with autosomal-dominant recurrent fever

OBJECTIVE

To investigate the presence of TRAPS (tumor necrosis factor receptor-associated periodic syndrome), which is a recently defined, dominantly inherited autoinflammatory syndrome caused by mutations in the tumor necrosis factor receptor superfamily 1A gene (TNFRSF1A, CD120a), in a Finnish family with recurrent fever.

METHODS

The TNFRSF1A gene was sequenced in both affected and unaffected family members. Flow cytometry and enzyme-linked immunosorbent assay analyses were used to assess membrane expression and serum levels of the TNFRSF1A protein, respectively.

RESULTS

A missense mutation in exon 4, located in the third extracellular domain of TNFRSF1A and resulting in an amino acid substitution (F112I) close to a conserved cysteine, was found in all 4 affected family members and in 1 asymptomatic individual. The mutation was clearly associated with low levels of soluble TNFRSF1A as well as with the clinical symptoms of recurrent fever and abdominal pain. Impaired shedding of TNFRSF1A after phorbol myristate acetate stimulation was detected in blood granulocytes and monocytes from the 3 adult family members with the mutation, but in the child bearing the mutation and showing clinical symptoms of recent onset, the shedding defect was less marked.

CONCLUSION

TRAPS should be suspected in any patient who presents with a history of intermittent fever accompanied by unexplained abdominal pain, arthritis, or skin rash, particularly in the presence of a family history of such symptoms. Screening for low serum levels of soluble TNFRSF1A identifies individuals who are likely to have TNFRSF1A mutations.

An Israeli Arab patient with a de novo TNFRSF1A mutation causing tumor necrosis factor receptor-associated periodic syndrome

OBJECTIVE

To investigate genetic susceptibility to recurrent fevers, generalized severe myalgia, and migratory erythema in an Israeli Arab child with no family history of similar disease.

METHODS

DNA sequencing of exons 1-6 of the TNFRSF1A gene (formerly TNFR1) was performed in the patient and his parents to determine the presence of the autosomal-dominant tumor necrosis factor receptor-associated periodic syndrome (TRAPS); informative markers spanning the TNFRSF1A locus were used to genotype all available members of the patient's family. The TNFRSF1A gene was subsequently screened in 69 healthy Arab controls and 96 Caucasian controls. Formal forensic paternity testing was performed on the child.

RESULTS

We found a de novo missense mutation in exon 3 of the TNFRSF1A gene, involving a novel C-->T transition encoding a Cys70Arg (C70R) variant, in the Israeli Arab patient. Eight of the common familial Mediterranean fever (FMF) gene MEFV mutations were excluded. This mutation was not present in the parents or siblings, or among the 69 healthy Arab controls. However, another TNFRSF1A variant, Pro46Lys (P46L), was present in 1 of the Arab controls.

CONCLUSION

We have identified a TNFRSF1A mutation associated with periodic fever in an Arab patient, and a TNFRSF1A variant, which is variably pathogenic in Caucasians, in an Arab control. This is the first report of a de novo mutation in periodic fevers in general, and also of TRAPS in the Arab population. These findings demonstrate the need to include TRAPS in the differential diagnosis of recurrent fevers in this population.

Genetically determined recurrent fevers

The usefulness of molecular diagnosis is now well established for genetically determined recurrent fevers. In familial Mediterranean fever, the severity of the disease and the risk of renal amyloidosis are correlated with mutations in MEFV, and the serum amyloid-associated protein (SAA)1 alpha/alpha allele is a modifying factor for amyloidosis. Study of the genes in various species shows that the human mutations represent a reappearance of the ancestral amino acid state and the B30-2 domain, where most human mutations are localized, is absent in the rat and mouse proteins. Since the discovery of the responsible gene, TNF-receptor-associated periodic syndrome seems to be more frequent than previously considered. Among the new mutations described, some are associated with an incomplete penetrance.

The tumor-necrosis-factor receptor-associated periodic syndrome: new mutations in TNFRSF1A, ancestral origins, genotype-phenotype studies, and evidence for further genetic heterogeneity of periodic fevers

Mutations in the extracellular domain of the 55-kD tumor-necrosis factor (TNF) receptor (TNFRSF1A), a key regulator of inflammation, define a periodic-fever syndrome, TRAPS (TNF receptor-associated periodic syndrome [MIM 142680]), which is characterized by attacks of fever, sterile peritonitis, arthralgia, myalgia, skin rash, and/or conjunctivitis; some patients also develop systemic amyloidosis. Elsewhere we have described six disease-associated TNFRSF1A mutations, five of which disrupt extracellular cysteines involved in disulfide bonds; four other mutations have subsequently been reported. Among 150 additional patients with unexplained periodic fevers, we have identified four novel TNFRSF1A mutations (H22Y, C33G, S86P, and c.193-14 G-->A), one mutation (C30S) described by another group, and two substitutions (P46L and R92Q) present in approximately 1% of control chromosomes. The increased frequency of P46L and R92Q among patients with periodic fever, as well as functional studies of TNFRSF1A, argue that these are low-penetrance mutations rather than benign polymorphisms. The c.193-14 G-->A mutation creates a splice-acceptor site upstream of exon 3, resulting in a transcript encoding four additional extracellular amino acids. T50M and c.193-14 G-->A occur at CpG hotspots, and haplotype analysis is consistent with recurrent mutations at these sites. In contrast, although R92Q also arises at a CpG motif, we identified a common founder chromosome in unrelated individuals with this substitution. Genotype-phenotype studies identified, as carriers of cysteine mutations, 13 of 14 patients with TRAPS and amyloidosis and indicated a lower penetrance of TRAPS symptoms in individuals with noncysteine mutations. In two families with dominantly inherited disease and in 90 sporadic cases that presented with a compatible clinical history, we have not identified any TNFRSF1A mutation, despite comprehensive genomic sequencing of all of the exons, therefore suggesting further genetic heterogeneity of the periodic-fever syndromes.

Autosomal-dominant periodic fever with AA amyloidosis: Novel mutation in tumor necrosis factor receptor 1 gene Rapid Communication

BACKGROUND

The recent identification of genes responsible for syndromes of periodic fever with amyloidosis has opened the way to a molecular diagnosis of hereditary AA amyloidosis.

METHODS

A Belgian woman presented for genetic counseling. Three first-degree relatives had a diagnosis of renal amyloidosis with a history of recurrent fever and inflammatory episodes. Medical records and pathological specimens were obtained from all physicians who had been in charge of her three relatives. Immunohistochemical staining was performed on paraffin-embedded material. A mutation search was performed in the MEFV (Mediterranean fever) and tumor necrosis factor receptor 1 (TNFR1 or TNFRSF1A) genes causing familial Mediterranean fever (FMF) and tumor necrosis factor receptor-associated periodic syndrome (TRAPS), respectively.

RESULTS

The family history was consistent with autosomal-dominant transmission of periodic fever with arthralgias, abdominal pain, and eventual AA amyloidosis involving the kidneys, digestive tract, and thyroid. Recurrent amyloidosis in kidney graft was demonstrated in one patient and was suspected in the other. A novel heterozygous mutation (C55S) in TNFRSF1A was identified in the affected patient available for genetic testing but not in the asymptomatic woman requiring counseling. No mutation was detected in MEFV.

CONCLUSIONS

We report a novel mutation (C55S) in TNFRSF1A, resulting in autosomal-dominant periodic fever and AA amyloidosis. This condition, known as TRAPS, should be added to the differential diagnosis of hereditary renal amyloidosis, with obvious implications for management and genetic counseling.