Differential mutational profiles of familial Mediterranean fever in North Africa.

Familial Mediterranean fever (FMF) is a recessive autoinflammatory disease, mainly occurring in the eastern Mediterranean. In these populations, the five FMF founder mutations are differently distributed. In Algeria, the FMF-causing variants remain poorly explored. This retrospective study aims to report the mutational profile of Algerian FMF patients and to compare it with North African FMF patients. One hundred eighty-three unrelated patients clinically suspected of FMF were recruited from various Algerian hospitals (2007-2015) and tested for mutations in exon 10 of MEFV gene. Molecular analysis identified 144 mutant alleles among 87 of 183 patients (47.5%). p.M694I was the most prevalent pathogenic allele, accounting for 63.2% of mutant alleles, followed by p.M694V and p.M680I occurring with a same frequency (14.5%). Others, p.A744S (6.2%) and p.I692del (1.3%), are less frequent. Interestingly, p.M694I was the most recurrent in patients with renal AA-amyloidosis. Our results provide the first genetic data on FMF in Algeria, demonstrating the predominance of p.M694I and the absence of p.V726A, compared to other North African countries (Morocco, Tunisia, and Egypt). In conclusion, North African FMF patients display differential mutational profiles that may result from the difference in ethnic origin and the genetic heterogeneity among these populations.

Validation of the new classification criteria for hereditary recurrent fever in an independent cohort: experience from the JIR Cohort Database.

OBJECTIVE: The new classification criteria for the hereditary recurrent fever (HRF) syndrome [cryopyrin-associated periodic syndrome (CAPS), TNF-α receptor-associated periodic syndrome (TRAPS), FMF and mevalonate kinase deficiency] have been published recently. These criteria define two core sets of criteria for each HRF: mixed criteria, including genetic and clinical variables, and clinical criteria, relying on clinical variables only. Our aim was to validate the criteria for HRF in an independent cohort, the JIR Cohort database, an international repository of systemic inflammatory diseases. METHODS: We enrolled patients with HRF, periodic fever, adenitis, pharyngitis and aphthous stomatitis syndrome (PFAPA) and syndrome of undefined recurrent fever (SURF). A score ranging from zero to two was attributed to their respective genotypes: zero (no mutation), one (non-confirmatory genotype) or two (confirmatory genotype). The criteria were applied to all patients based on genotype scoring. The treating physician's diagnosis served as the gold standard for the determination of specificity. RESULTS: We included 455 patients. The classification criteria showed excellent specificity for CAPS and TRAPS (98% specificity each), fair specificity for FMF (88%), but poor specificity for mevalonate kinase deficiency (58%). Sub-analysis showed excellent accuracy of the mixed criteria for all four HRFs. Misclassification was mainly attributable to clinical criteria sets, with false-positive patients in all four HRF clinical criteria sets. CONCLUSION: This study represents the final validation step of the HRF classification criteria as recommended by the ACR. Genetic data appear to be necessary to classify patients with HRF correctly.

Performance of recently proposed periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome criteria in a region endemic for familial Mediterranean fever.

The periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is an auto-inflammatory condition characterized by recurrent episodes of fever accompanied by aphthosis, cervical adenitis, and pharyngitis. Diagnosis of PFAPA could be challenging due to clinic overlap with familial Mediterranean fever (FMF). An international consensus has been established recently, to define a new set of classification criteria for PFAPA syndrome. We aimed to evaluate the performance of recently proposed PFAPA criteria, to assess their utility in FMF regions. Patients diagnosed with PFAPA syndrome, FMF, and juvenile idiopathic arthritis (JIA) were included. Two investigators blindly evaluated all of patients for the newly proposed PFAPA criteria. A total of 542 patients (322 with PFAPA syndrome, 118 FMF and 102 JIA) were evaluated. Mean age of patients was 6.6 ± 2.81, 12.75 ± 3.9, and 12.42 ± 4.8 years for PFAPA, FMF, and JIA, respectively. We found quite high sensitivity (89.7%) but insufficient specificity of newly proposed PFAPA criteria (69.5%). When applied to control patients separately, specificity was found to be 61% and 79.4% for FMF and JIA patients, respectively. Positive predictive value was 81%, while negative predictive value was 82%. Recently proposed PFAPA criteria have satisfactory sensitivity, but its specificity is still under expectation. There is a need for a distinctive criterion between PFAPA syndrome and FMF, in FMF endemic regions, e.g., cryptic tonsillitis rapidly responsive to single dose of glucocorticoids. Further studies with higher patients' number in different regions are needed.

Performance of the new 'Eurofever/PRINTO classification criteria' in FMF patients.

OBJECTIVE: Recently a new set of criteria proposed for the classification of auto inflammatory recurrent fevers including familial Mediterranean Fever (FMF). We aimed to compare the sensitivity and specificity of the new Eurofever/PRINTO classification criteria with those of the Tel Hashomer and Yalcinkaya-Ozen criteria. METHODS: 151 consecutive FMF patients between February and May 2019 who were followed at Hacettepe University Department of Pediatric Rheumatology were included in this study. A group of 82 patients with periodic fever 66 periodic fever, aphthosis, pharyngitis and adenitis syndrome (PFAPA), nine cryopyrin-associated periodic syndrome (CAPS) and seven mevalonate kinase deficiency/hyperimmunoglobulin D syndrome (MKD/HIDS) patients) served as controls. GraphPad 6.0 was used for statistical analysis. RESULTS: Three different classification criteria were analyzed in 151 FMF patients with a median age at diagnosis of 5 years and in 82 controls with a median age at diagnosis of 3 years. The sensitivity of the new Eurofever/PRINTO criteria (96%) was highest (Tel Hashomer criteria-88.4% and Yalcinkaya-Ozen criteria-93.4%). However, the specificity of these criteria (73.1%) was lowest (Tel Hashomer criteria-92.6% and Yalcinkaya-Ozen criteria-84.1%). The new Eurofever/PRINTO criteria achieved the highest sensitivity (100%) in biallelic exon 10 mutation patients (Tel Hashomer criteria-87.4% and Yalcinkaya-Ozen criteria-94.2%). However, the new set had the lowest sensitivity (88.2%) in heterozygote exon 10 mutation patients (Tel Hashomer criteria 94.1% and Yalcinkaya-Ozen criteria 94.1%). CONCLUSION: In this Turkish cohort, the new Eurofever/PRINTO criteria have a better sensitivity but lower specificity with higher misclassifications than other two well-known criteria. The combination of clinical manifestations with genotype increased the sensitivity. The lower specificity may be due to the high carrier rate in our population. Although the ethnicity information lowers the specificity, 'clinical-only' criteria set may still guide the clinician to perform appropriate genetic testing in patients with recurrent fever.

Performance of Tel-Hashomer, Livneh, pediatric and new Eurofever/PRINTO classification criteria for familial Mediterranean fever in a referral center.

Until now, the diagnosis of familial Mediterranean fever (FMF) was based on validated subsets of clinical criteria, but recently new Eurofever/PRINTO classification criteria concerning genetic analyses were proposed. The study aimed to compare the performances of three validated diagnostic criteria (Tel-Hashomer, Livneh, pediatric criteria) and new Eurofever/PRINTO classification criteria. The medical charts of study and control groups were reviewed retrospectively. Patients were evaluated for three diagnostic criteria and new Eurofever/PRINTO classification criteria. Control group consists of patients with other autoinflammatory diseases. A total of 1291 patients were classified into three groups according to their mutations: group 1: 447 patients with homozygous mutations; group 2: 429 patients with compound heterozygous mutations; and group 3: 415 patients with one heterozygous mutation. Similar diagnostic utility was found according to Livneh criteria between groups. But, proportion of patients fulfilling Tel-Hashomer and pediatric criteria was higher in groups 1 and 2. According to Eurofever/PRINTO criteria, 98.2% of patients with homozygous mutations, 94.2% of patients with compound heterozygous mutations and 80.2% of patients with heterozygous mutations were classified as FMF. In control group, 99.2% of them fulfilled the Livneh criteria, 66.9% met the pediatric criteria and 0.8% satisfied the Tel-Hashomer criteria, while none of control patients met the Eurofever/PRINTO classification criteria. Performances of three validated diagnostic criteria and new Eurofever/PRINTO classification criteria for FMF were similar and provide high utility in diagnosing/classifying patients with homozygous and compound heterozygous mutations. However, both Eurofever/PRINTO classification criteria and Tel-Hashomer criteria had significantly lower performance in heterozygous patients.

Classification criteria for autoinflammatory recurrent fevers.

BACKGROUND: Different diagnostic and classification criteria are available for hereditary recurrent fevers (HRF)-familial Mediterranean fever (FMF), tumour necrosis factor receptor-associated periodic fever syndrome (TRAPS), mevalonate kinase deficiency (MKD) and cryopyrin-associated periodic syndromes (CAPS)-and for the non-hereditary, periodic fever, aphthosis, pharyngitis and adenitis (PFAPA). We aimed to develop and validate new evidence-based classification criteria for HRF/PFAPA. METHODS: Step 1: selection of clinical, laboratory and genetic candidate variables; step 2: classification of 360 random patients from the Eurofever Registry by a panel of 25 clinicians and 8 geneticists blinded to patients' diagnosis (consensus ≥80%); step 3: statistical analysis for the selection of the best candidate classification criteria; step 4: nominal group technique consensus conference with 33 panellists for the discussion and selection of the final classification criteria; step 5: cross-sectional validation of the novel criteria. RESULTS: The panellists achieved consensus to classify 281 of 360 (78%) patients (32 CAPS, 36 FMF, 56 MKD, 37 PFAPA, 39 TRAPS, 81 undefined recurrent fever). Consensus was reached for two sets of criteria for each HRF, one including genetic and clinical variables, the other with clinical variables only, plus new criteria for PFAPA. The four HRF criteria demonstrated sensitivity of 0.94-1 and specificity of 0.95-1; for PFAPA, criteria sensitivity and specificity were 0.97 and 0.93, respectively. Validation of these criteria in an independent data set of 1018 patients shows a high accuracy (from 0.81 to 0.98). CONCLUSION: Eurofever proposes a novel set of validated classification criteria for HRF and PFAPA with high sensitivity and specificity.

An International Delphi Survey for the Definition of New Classification Criteria for Familial Mediterranean Fever, Mevalonate Kinase Deficiency, TNF Receptor-associated Periodic Fever Syndromes, and Cryopyrin-associated Periodic Syndrome.

OBJECTIVE: Provisional evidence-based classification criteria for hereditary periodic fever (HPF) have been recently developed. However, no consensus on how to combine clinical criteria, laboratory tests, and results of molecular analysis has been reached. The objective of this study is to understand which variables physicians consider important for the classification of patients with HPF. METHODS: Two Delphi surveys were sent to health professionals in the field of autoinflammation. In the first open survey, 124 researchers could list all the variables they consider useful for the diagnosis of each monogenic periodic fever. The variables could be of any type and each researcher could complete the survey for 1 or more diseases. In the second survey, 162 researchers were asked to select, from a list of items coming from the first survey, the 10 top variables and to rank them by assigning a score from 10 to 1. RESULTS: The response rates to the Delphi surveys were 85% for the first session and 87% for the second. The variables selected for each disease (corresponding to the third quartile, considering the total score obtained by the variables after the second Delphi survey) were 21 for mevalonate kinase deficiency, 22 for cryopyrinopathies, 18 for familial Mediterranean fever, and 20 for tumor necrosis factor receptor-associated periodic fever syndrome. A positive genetic test reached the top rank in all the HPF. CONCLUSION: Our process led to the identification of those features considered the most important as candidate variables to be included in a new set of evidence-based classification criteria for HPF.

Which definition should be used to determine colchicine resistance among patients with familial Mediterranean fever?

OBJECTIVES: Colchicine is the main therapy for familial Mediterranean fever (FMF); however, 5-10% of patients are colchicine-resistant. There is no standard and validated definition for colchicine resistance. We aimed to compare the existing definitions for colchicine resistance in both adult and paediatric FMF patients to find out the best definition to determine colchicine-resistant patients. METHODS: 385 FMF patients were evaluated and patients receiving anti-interleukin-1 treatment were included. The anti-IL-1 therapy had been initiated by the experts in the past based on their experience. Eleven different definitions (found out after PubMed search for colchicine resistance in FMF) were applied to all patients. Results were re-analysed after excluding the patients who had no clinical attacks but persistently high acute phase reactants (APRs) and/or amyloidosis. RESULTS: Sixty patients (40 adults/20 children) who had been using anti-IL-1 therapy were included into this study as colchicine-resistant patients. The highest percentage of patients fulfilled definition 5 (93.3%). Definition 9 had the poorest performance (26%). Significantly, a higher percentage of adult patients met definitions 4 and 6 than paediatric patients (87.5% vs. 50%, p=0.002; 75% vs. 40%, p=0.008, respectively). After excluding patients without clinical attacks, the highest percentage of patients fulfilled definition 2 (94.4%). We combined the attack frequency (>1 typical episode/3 months) in definition 2 and presence of amyloidosis/APR increase (increase in ≥2/3 APRs) in definition 5 to create a new definition which was met by 59 (98.3%) colchicine-resistant FMF patients. CONCLUSIONS: Definition of colchicine resistance is still controversial. Definitions with both clinical and laboratory criteria were met by a higher percentage of resistant patients than those without laboratory criteria. However, the proper definitions for the attack-free period and persistence of APRs are still lacking.

Performance of Different Diagnostic Criteria for Familial Mediterranean Fever in Children with Periodic Fevers: Results from a Multicenter International Registry.

OBJECTIVE: Our aims were to validate the pediatric diagnostic criteria in a large international registry and to compare them with the performance of previous criteria for the diagnosis of familial Mediterranean fever (FMF). METHODS: Pediatric patients with FMF from the Eurofever registry were used for the validation of the existing criteria. The other periodic fevers served as controls: mevalonate kinase deficiency (MKD), tumor necrosis factor receptor-associated periodic syndrome (TRAPS), cryopyrin-associated periodic syndrome (CAPS), aphthous stomatitis, pharyngitis, adenitis syndrome (PFAPA), and undefined periodic fever from the same registry. The performances of Tel Hashomer, Livneh, and the Yalcinkaya-Ozen criteria were assessed. RESULTS: The FMF group included 339 patients. The control group consisted of 377 patients (53 TRAPS, 45 MKD, 32 CAPS, 160 PFAPA, 87 undefined periodic fevers). Patients with FMF were correctly diagnosed using the Yalcinkaya-Ozen criteria with a sensitivity rate of 87.4% and a specificity rate of 40.7%. On the other hand, Tel Hashomer and Livneh criteria displayed a sensitivity of 45.0 and 77.3%, respectively. Both of the latter criteria displayed a better specificity than the Yalcinkaya-Ozen criteria: 97.2 and 41.1% for the Tel Hashomer and Livneh criteria, respectively. The overall accuracy for the Yalcinkaya-Ozen criteria was 65 and 69.6% (using 2 and 3 criteria), respectively. Ethnicity and residence had no effect on the performance of the Yalcinkaya-Ozen criteria. CONCLUSION: The Yalcinkaya-Ozen criteria yielded a better sensitivity than the other criteria in this international cohort of patients and thus can be used as a tool for FMF diagnosis in pediatric patients from either the European or eastern Mediterranean region. However, the specificity was lower than the previously suggested adult criteria.

Evidence-based provisional clinical classification criteria for autoinflammatory periodic fevers.

The objective of this work was to develop and validate a set of clinical criteria for the classification of patients affected by periodic fevers. Patients with inherited periodic fevers (familial Mediterranean fever (FMF); mevalonate kinase deficiency (MKD); tumour necrosis factor receptor-associated periodic fever syndrome (TRAPS); cryopyrin-associated periodic syndromes (CAPS)) enrolled in the Eurofever Registry up until March 2013 were evaluated. Patients with periodic fever, aphthosis, pharyngitis and adenitis (PFAPA) syndrome were used as negative controls. For each genetic disease, patients were considered to be 'gold standard' on the basis of the presence of a confirmatory genetic analysis. Clinical criteria were formulated on the basis of univariate and multivariate analysis in an initial group of patients (training set) and validated in an independent set of patients (validation set). A total of 1215 consecutive patients with periodic fevers were identified, and 518 gold standard patients (291 FMF, 74 MKD, 86 TRAPS, 67 CAPS) and 199 patients with PFAPA as disease controls were evaluated. The univariate and multivariate analyses identified a number of clinical variables that correlated independently with each disease, and four provisional classification scores were created. Cut-off values of the classification scores were chosen using receiver operating characteristic curve analysis as those giving the highest sensitivity and specificity. The classification scores were then tested in an independent set of patients (validation set) with an area under the curve of 0.98 for FMF, 0.95 for TRAPS, 0.96 for MKD, and 0.99 for CAPS. In conclusion, evidence-based provisional clinical criteria with high sensitivity and specificity for the clinical classification of patients with inherited periodic fevers have been developed.

Familial Mediterranean fever: new phenotypes.

Familial Mediterranean fever (FMF) is an inherited autosomal recessive disorder, ethnically restricted and commonly found among individuals of Mediterranean descent, caused by MEditerranean FeVer gene (MEFV) mutations on chromosome 16. It is the most frequent periodic febrile syndrome among the autoinflammatory syndromes. Clinically, FMF can be distinguished into three phenotypes: type 1, which is commonly associated with recurrent short episodes of inflammation and serositis, including fever, peritonitis, synovitis, pleuritis, but also pericarditis, orchitis or meningitis episodes; type 2, characterized by the evidence of reactive amyloid-associated (AA) amyloidosis, the most severe complication of FMF, as the first clinical manifestation of the disease in an otherwise asymptomatic individual; type 3, referred to the 'silent' homozygous or compound heterozygote state, in which two MEFV mutations are detected without signs or symptoms of FMF nor of AA amyloidosis. In the recent years it has been observed that also heterozygous mutation carriers can suffer from a mild or incomplete form of FMF, named 'FMF-like' disease. The influence of other modifiers genes and/or environmental factors can contribute to the variable penetrance and to the phenotypic variability of FMF. The insight into complex clinical and genetic cases will provide adjunctive details for the comprehension of the mechanisms of this kaleidoscopic disease.

Role of the R92Q TNFRSF1A mutation in patients with familial Mediterranean fever.

OBJECTIVE: To define the frequency of the R92Q tumor necrosis factor receptor-associated periodic syndrome (TRAPS) mutation in patients with familial Mediterranean fever (FMF) and to study the role of this mutation in FMF. METHODS: Ninety-two FMF patients and 250 controls were genotyped for the R92Q mutation. The frequency of R92Q was assessed among 5 groups of FMF patients. RESULTS: R92Q was found in 6% of the controls, with an especially high carrier rate among Moroccan Jews (8%). R92Q was found in 3 (3.2%) of the 92 FMF patients, 1 homozygous for the MEFV M694V mutation and 2 heterozygous for M694V. All 3 patients showed partial response to colchicine. R92Q was not found in patients unresponsive to colchicine, nor was it found in patients with amyloidosis or in patients with FMF-like disease without MEFV mutations. CONCLUSION: The frequency of the R92Q mutation in FMF patients is comparable with that of controls. Despite the fact that TRAPS and FMF share common biochemical pathways, we found no evidence for an interaction between these two genes.

Evaluation of disease severity in familial Mediterranean fever.

OBJECTIVE: To establish a new, objective, statistically based severity score for familial Mediterranean fever (FMF). METHODS: One hundred consecutive FMF patients were evaluated independently by 2 FMF experts for severity of their disease and were assigned to 1 of 3 severity levels: mild, intermediate, or severe. Nine candidate criteria, reflecting objective suffering and disability, were analyzed to determine their weight for patient placement in the 3 predefined severity groups. RESULTS: Candidate criteria best differentiating between the 3 patient categories were the frequency of attacks, the number of sites affected during an attack and during the course of the disease, and the duration of the attacks. These criteria were applied in a classification-tree model to establish a new FMF-severity score (F-SS). The first set of F-SS (F-SS-1) was highly sensitive and specific. Integrating F-SS-1 with clinical parameters strongly associated with disease severity resulted in a simplified score, the second set of F-SS (F-SS-2). CONCLUSIONS: New, useful, objective, and valid severity scores were established and found to distinguish between patients with mild, intermediate, and severe diseases with high sensitivity and specificity. RELEVANCE: The F-SS established may be important for treatment decisions, prognosis evaluation, and comparative analysis of patient populations.

[Hyper-IgD syndrome and other hereditary periodic fever syndromes]. / La sindrome da Iper-IgD e altre sindromi febbrili periodiche ereditarie.

Hereditary periodic fever syndromes are a group of systemic disorders characterized by recurrent attacks of systemic inflammation (autoinflammation) without infectious or autoimmune cause. The hyper-IgD syndrome (HIDS) is a rare autosomal recessive inflammatory disorder characterized by recurrent fever, increased serum IgD (normal value < 100 U/ml) and generalized inflammation (lymphadenopathy, arthralgias/arthritis, abdominal complaints, skin rash, and headache). The attacks persist during the entire life although frequency and severity tend to diminish with age. HIDS is caused by specific mutations in the gene encoding mevalonate kinase, resulting in depressed enzymatic activity. At present the therapy for the syndrome is only supportive. Other than HIDS, other hereditary systemic inflammatory disorders have been described: the Familial Mediterranean Fever, the tumour necrosis factor receptor associated periodic syndrome (TRAPS), a disease related to the mutations of one of the TNF receptors, the Familial Cold Urticaria and the Muckle-Wells syndrome. The differential diagnosis with other causes of periodic fever is crucial for assessing appropriate management and treatment.

Autoinflammatory diseases: the hereditary periodic fever syndromes.

Human autoinflammatory diseases (HAIDs) are a heterogeneous group of genetically determined affections characterized by seemingly unprovoked inflammation, in the absence of autoimmune or infective causes. The hereditary periodic fever syndromes (HPFSs) are a HAID subset consisting of three main nosologic entities: familial Mediterranean fever (FMF), hyperimmunoglobulinemia D and periodic fever syndrome (HIDS), and tumor necrosis factor receptor superfamily 1A-associated periodic syndrome (TRAPS). FMF and HIDS are autosomal recessive diseases, while TRAPS is dominantly inherited. Although each HPFS presents genetic and phenotypic peculiarities, globally these affections share an intermittent expression, in form of acute attacks of fever variably associated with serosal, synovial and/or cutaneous inflammation, usually self-limiting. Amyloidosis is the most severe, life-threatening complication of FMF and TRAPS, whereas it has not been till now reported in HIDS. The HPFS molecular bases have been recently identified. In this paper, the most recent information on HPFSs is reviewed and summarized.

Periodic fever syndromes--a clinical overview.

Most hereditary periodic fever syndromes known today have their onset in the first year of life. Only two, namely Familial Mediterranean Fever (FMF) and TNF-Receptor Associated Periodic Syndrome (TRAPS) occur later, with most patients having become symptomatic by their twentieth birthday. Therefore this review will concentrate on FMF and TRAPS, the latter being a very rare disease, while the former has become somewhat more common in mid-Europe as a result of migration.

From renal amyloid deposits to the identification of the culprit genes.

Hereditary amyloidoses with renal involvement are classified in two groups. The first group is a growing family of autoinflammatory disorders characterized by recurrent fever attacks. Amyloidosis is caused by the deposition of amyloid A (AA) protein, which is a degradation product of a normal serum acute-phase protein: serum amyloid A (SAA). The prototype is familial Mediterranean fever (FMF). TNF Receptor Associated Periodic Syndrome (TRAPS) is a recently recognized periodic fever syndrome, differing from FMF in several characteristics: autosomal-dominant transmission, longer duration of attacks, and lack of response to colchicine prophylaxis. The second group comprises a variety of disorders, each characterized by the deposition of a specific mutant protein. The prototype is transthyretin amyloidosis (TTR). Identification of the form of amyloidosis has clinical implications. Therefore, in a patient with a history of recurrent fever attacks and AA amyloidosis, a diagnosis of FMF or TRAPS dictates appropriate genetic counseling and management. In patients with renal amyloidosis without a history of fever, identification of the mutant protein is therapeutically crucial; therefore, when the cell type that produces the precursor is (exclusively or mainly) the hepatocyte, a liver transplantation is to be considered.

Hereditary periodic fever syndromes.

Hereditary periodic fever syndromes are defined by recurrent attacks of generalised inflammation for which no infectious or auto-immune cause can be identified. For most of these disorders, the molecular basis has recently been elucidated. This has opened the prospect of novel therapeutic approaches. Familial Mediterranean fever (FMF) is caused by mutations in the MEFV gene. Pathogenesis is poorly understood. The clinical severity is in part related to the mutations involved. Tumour necrosis factor receptor-1-associated periodic syndrome (TRAPS) is caused by mutations in the TNFRSF1A gene. This results in decreased serum levels soluble TNF-receptor leading to inflammation due to unopposed TNF-alpha action. Results of treatment with recombinant TNF-receptor analogues are promising. The hyper IgD periodic fever syndrome (HIDS) is caused by mutations in the MVK gene, leading to mevalonate kinase deficiency. The pathogenesis remains unclear. Muckle-Wells syndrome (MWS) and familial cold urticaria (FCU) are probably allelic disorders. The gene has been located, but not identified.