Familial periodic fever and amyloidosis due to a new mutation in the TNFRSF1A gene

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

OBJECTIVES

Tumor necrosis factor (TNF) receptor-1 associated periodic syndrome (TRAPS) is a rare autosomal dominant autoinflammatory disorder associated with mutations in the TNF receptor super family 1A (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 center 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 February 2021 following the PRISMA 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: 3 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, 7 stabilized and 4 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.

[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.

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.

Musculoskeletal disorders in secondary amyloidosis and hereditary fevers

Amyloidosis remains a severe potential complication of many chronic inflammatory disorders, foremost of rheumatoid arthritis. It is not exactly known why some patients develop a progressive amyloidosis while others do not, although latent deposits may be present. It is likely that more potent anti-inflammatory drugs recently used in rheumatoid arthritis have led to a decrease of amyloid-associated (AA) amyloidosis. However, overt amyloidosis remains a severe complication of some chronic inflammatory disorders and it has a poor prognosis. Hereditary fevers are a group of diseases characterized by intermittent bouts of clinical inflammation with focal organ involvement, mainly abdomen, musculoskeletal system and skin. The most frequent is familial Mediterranean fever which affects patients of Mediterranean descent all over the world. Three other types have been recently characterized clinically as well as genetically. A thorough diagnosis is warranted, as clinical and therapeutic management is specific for each of these diseases.

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.

Fever of unknown origin in adults: 40 years on

A revision of the criteria of fever of unknown origin (FUO), established in 1961, is desirable because of important evolutions in medical practice and the emergence of new patient populations. The development of rapid laboratory tests and powerful diagnostic tools, such as ultrasonography, computed tomography and magnetic resonance imaging often makes hospitalization unnecessary and new categories of patients such as those with HIV infection, neutropenia, immunosuppression and nosocomial illness require an approach different from classical FUO. The more then 200 reported causes of FUO can be classified into four diagnostic categories; infections, tumours, noninfectious inflammatory diseases (NIID) and miscellaneous. A uniform classification system is highly wanted to allow comparison between different series. The reports of the 1990s show slight changes in the distribution of causes, namely less infections, less tumours, more NIID and more undiagnosed cases. A uniform diagnostic strategy cannot be determined. The initial investigation should be directed by potentially diagnostic clues revealed by extensive history, meticulous physical examination and a standard set of laboratory tests. 18Fluoro-deoxy-glucose-positron-emitted-tomography is a new valuable total body scintigraphy in the search for the site of origin of the fever. In view of the rather good long-term prognosis, a wait-and-see strategy may be more appropriate than a systematic staged approach. Elderly patients and patients with episodic fever represent two specific groups of classical FUO that require a distinct approach. HIV-associated, nosocomial and neutropenic FUO should be considered as separate clinical entities.

[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.

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.