Phenotypic characterization of Familial Mediterranean Fever patients harboring variants of uncertain significance

Background/aim: Familial Mediterranean Fever (FMF) is the prototype of hereditary autoinflammatory disorders and caused by mutations on the MEFV gene located on the short arm of chromosome 16. Although some MEFV variants are clearly associated with disease phenotype, there are numerous variants with unknown clinical association which are termed as variants of uncertain significance (VUS). Here, we present clinical correlations of VUS in a large cohort of adult FMF patients from three tertiary centers located in Central Anatolia. Materials and methods: All patients were recruited from FMF in Central Anatolia (FiCA) cohort. Demographic (sex, age at disease onset) and clinical features (disease characteristics, attack frequency, mean colchicine dose, colchicine nonresponsiveness, amyloidosis, and persistent inflammation) of patients with VUS were compared with those harboring pathogenic variants. Disease severity and damage were also evaluated using international severity score for FMF (ISSF) and autoinflammatory disease damage index (ADDI), respectively. Results: Among 971 participants included, MEFV gene analysis results were available for 814 patients. Twenty-six (3.2%) patients had single heterozygous VUS and 54 (6.6%) had pathogenic/VUS complex heterozygous variants. Patients with single heterozygous VUS had similar demographic/clinical features, ISSF and ADDI scores compared to those with single heterozygous pathogenic variant (p > 0.05 for all). No difference was observed in the demographic and clinical features of patients with single heterozygous pathogenic mutation and pathogenic/VUS complex heterozygous variant (p > 0.05 for all). ISSF and ADDI scores were lower in pathogenic/VUS complex heterozygous patients than those harboring single pathogenic mutation (p = 0.006 and 0.004, respectively). Conclusion: Our findings suggest that patients with single heterozygous VUS has mild FMF phenotype similar to those with single pathogenic mutation. Pathogenic/VUS complex heterozygosity does not lead to a more severe clinical phenotype than having a single pathogenic variant.

MEFV mutation frequencies in a Turkish cohort with low prevalence of familial Mediterranean fever

Background/aim: Familial Mediterranean fever (FMF) is a genetically recessive autoinflammatory disease caused by mutations in the Mediterranean fever (MEFV) gene. The aim of this study was to investigate the frequencies of the most common MEFV mutations among a sample of healthy individuals from the Havsa population of European Turkey, where FMF is less prevalent compared to Asian Turkey. Materials and methods: The study group consisted of 263 unrelated healthy adults. All of the participants were analyzed for the M694V, V726A, M680I, and E148Q mutations in the MEFV gene. Results: In total, 25 of the 263 individuals carried MEFV mutations (9.5%). The observed allele frequencies were 1.5% for M694V (95% confidence interval [CI] 0.5-2.5), 2.6% for E148Q (95% CI 1.6-3.9), 0.5% for M680I (95% CI 0.0-1.1), and 0.0% for V726A. The frequencies of the M694V, M680I, and E148Q mutations were not significantly different from allele frequencies (approximately 20%) determined for other regions of Turkey where FMF is more prevalent. Conclusion: These data suggest that the positivity of the MEFV gene mutation tests have lower predictive value in a population with low FMF prevalence.

Familial Mediterranean fever in Chinese adult patients.

Objectives: FMF is the most frequent monogenic auto-inflammatory disease worldwide. There have been hardly any cases reported in the Chinese population. We aimed to describe the first cohort of adult FMF patients in China. Methods: We evaluated all the adult patients suffering from FMF referred to our centre from April 2015 through March 2017. Patients were diagnosed clinically according to the Tel Hashomer criteria. Whole exome sequencing was performed in each patient. Results: A total of 11 adult patients were diagnosed as FMF in our centre. The mean age of onset was 29.4 years (s.d. 18.2). All patients were of Chinese Han ethnicity with no positive family history. All patients had intermittent febrile episodes. During attacks, seven patients had generalized abdominal pain, three experienced chest pain, four developed arthritis and none reported erysipelas-like skin changes. No patient had evidence of AA amyloidosis. Every patient carried at least one variant in the MEFV gene. All patients had good response to colchicine. Conclusion: Our study is the first to suggest the presence of FMF in the Chinese adult population. The late onset, often atypical and mild clinical manifestations and absence of AA amyloidosis in our patients might be related to low-penetrance and heterozygous MEFV variants. Our results await to be confirmed on larger Chinese populations.

A retrospective study comparing the phenotype and outcomes of patients with polyarteritis nodosa between UK and Turkish cohorts.

There is a need for better definition of polyarteritis nodosa (PAN) subphenotypes and the influence of ethnicity and geography. This study is aimed to study the demographic and clinical features of PAN cohorts from the UK and Turkey (TR) and to compare and contrast disease characteristics. A retrospective survey of databases from two vasculitis centres between 1990 and 2016 for PAN patients fulfilling the EMEA Vasculitis Classification algorithm. All paediatric-onset adult patients met the Ankara 2008 (EULAR/PReS endorsed) criteria for childhood PAN. Those with typical angiographic and/or histopathologic findings consistent with PAN were included. 93 (M/F: 51/42) patients (UK: 47, TR: 46) were included. Three were HBV-related, 20 (21.5%) had paediatric onset and 16 (16.5%), cutaneous PAN. TR patients had younger age of disease onset 44 (28.5-59.0) vs. 24.5 (11.8-40.5), p = 0.002. Twelve (26%) of TR patients had monogenic disease (Familial Mediterranean Fever association (n = 7), deficiency of adenosine deaminase 2, DADA2, (n = 5). No difference was found in phenotype between paediatric and adult onset patients except for frequency of cutaneous lesions (p = 0.002). During a median 67.5 (32-126) months follow-up, 13 patients died (12.7% in UK vs. 15.2% in Turkish cohorts). No difference was found between two cohorts in relation to relapse rate, death and vasculitis damage index. This study defined a diagnosis of PAN according to the EMEA algorithm. The TR group had a younger age of disease onset and more cases of monogenic disease; however, disease extent, relapse rate, damage index and death rates were similar between groups.

Boundaries between familial Mediterranean fever and juvenile spondyloarthritis: Analysis of three French retrospective cohorts.

OBJECTIVES: Children with Familial Mediterranean fever may suffer from musculoskeletal involvement, somewhat difficult to distinguish from juvenile spondyloarthritis. The association of these two diseases has been scarcely reported in children. Objective of this work was to define the association of familial Mediterranean fever and juvenile spondyloarthritis in France. METHODS: Three cohorts of children with familial Mediterranean fever, juvenile spondyloarthritis, familial Mediterranean fever related juvenile spondyloarthritis, were retrospectively identified in the French reference center of auto-inflammatory diseases. Familial Mediterranean fever was defined according to Tel-Hashomer or Turkish pediatric criteria with at least one exon-10 MEFV-gene mutation. Juvenile spondyloarthritis was defined according to ILAR criteria. Patients with familial Mediterranean fever or juvenile spondyloarthritis were respectively compared to familial Mediterranean fever related juvenile spondyloarthritis patients. RESULTS: Sixteen children were identified as having familial Mediterranean fever related juvenile spondyloarthritis. The male/female-ratio was 0.6, with median age at spondyloarthritis onset of 7.5years (3-16years). All carried at least one M694V variant in MEFV gene; 16.7% were HLA-B27-carriers. Compared to 83 familial Mediterranean fever patients, familial Mediterranean fever related juvenile spondyloarthritis patients had less frequently fever (P<0.01) and more frequently arthritis (P<0.05), enthesitis (P<0.001), inflammatory back pain (P<0.001), inadequate response to colchicine (P<0.05). Compared to 20 juvenile spondyloarthritis patients, familial Mediterranean fever related juvenile spondyloarthritis patients less often received non-steroidal anti-inflammatory drugs (P<0.01) and anti-tumor necrosis factor drugs (P<0.001). CONCLUSIONS: Familial Mediterranean fever may be associated with typical pattern of juvenile spondyloarthritis. These patients, with less response to colchicine, should be diagnosed earlier and treated as for jSpA.

Egyptian tale from India: application of whole-exome sequencing in diagnosis of atypical familial Mediterranean fever.

Clinical diagnosis of autoinflammatory diseases requires a high degree of clinical suspicion and clinching molecular evidence to substantiate the diagnosis. This is more so in populations with low prevalence of these disorders. In this report, we describe the case of a young man from India with recurrent fever and persistent arthritis. The patient's forefathers were of Egyptian ancestry who practiced consanguinity. Molecular genetic analysis using whole-exome sequencing suggested the presence of variants c.443A>T:p.E148V and c.442G>C:p.E148Q in the MEFV gene, earlier independently shown to be associated with familial Mediterranean fever (FMF) in a compound heterozygous state. The variants were further confirmed by capillary sequencing. This report also highlights the application of whole exome sequencing to delineate the allelic differences in the variants apart from serving as a quick genetic screening approach for autoinflammatory diseases. To the best of our knowledge, this is the first report of a compound heterozygosity for the two well-characterized variants associated with atypical FMF in a patient.

Prevalence of common MEFV mutations and carrier frequencies in a large cohort of Iranian populations.

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder caused by mutations in the MEFV gene. The disease is especially common among Armenian, Turkish, Jewish and Middle East Arab populations. To identify the frequency and the spectrum of common MEFV mutations in different Iranian populations, we investigated a cohort of 208 unselected asymptomatic individuals and 743 FMF patients. Nine hundred and fifty-one samples were analysed for the presence of 12 MEFV mutations by PCR and reverse-hybridization (FMF StripAssay, ViennaLab, Vienna, Austria). Confirmatory dideoxy sequencing of all MEFV gene exons was performed for 39 patients. Fifty-seven (27.4%) healthy individual carried mutant MEFV alleles. Three hundred and ninety-one (52.6%) FMF patients were found positive for either one (172/743; 23.1%), two or three MEFV mutations. Using dideoxy sequencing, three novel variants, A66P, R202W and H300Q, could be identified. Our analysis revealed an allele frequency and carrier rate of 15.6 and 27.4%, respectively, among healthy Iranians. Still moderate compared to neighbouring Armenia, but higher than in Turkey or Iraq, these data suggest that FMF is remarkably common among Iranian populations. E148Q was most frequent in the group of healthy individuals, whereas M694V was the most common mutation among FMF patients, thereby corroborating previous studies on MEFV mutational spectra in the Middle East. Accordingly, MEFV mutations are frequent in healthy Iranian individuals across different ethnic groups. Based on this finding, the awareness for FMF and the implementation of augmented carrier screening programmes considering the multiethnic nature of the Iranian population should be promoted.

Mutational Spectrum of the MEFV Gene in AA Amyloidosis Associated With Familial Mediterranean Fever.

INTRODUCTION: Familial Mediterranean fever (FMF) is a recessively inherited disease which is characterized by recurrent episodic fever, abdominal pain, and polyserositis. It is caused by mutations in the MEFV gene, encoding the pyrin protein. The most important complication of FMF is secondary (AA) amyloidosis that leads to kidney failure. This study aimed to identify the frequency and distribution of MEFV mutations in Turkish patients with FMF-associated AA amyloidosis. MATERIALS AND METHODS: A total of 57 patients with FMF-associated AA amyloidosis and 60 healthy controls were included in this study. We analyzed the MEFV gene for E148Q, M694V, M680I, and V726A mutations and R202Q variant by polymerase chain reaction and restriction fragment length polymorphism methods.  Results. The male-female ratio was 0.72. The mean age of the patients was 29.8 ± 12.8 years. Among the patients, the rate of the MEFV mutations was found to be 77.2%. The most frequently observed genotype was homozygous M694V mutation, which was present in 17 patients (29.8%, P < .001), followed by compound heterozygous M680I/M694V (14.3%, P = .01). The R202Q allele frequencies were significantly different between patients and control group (P = .02; odds ratio, 0.53; 95% confidence interval, 0.30 to 0.94). CONCLUSIONS: In this study, mutation analysis of MEFV gene confirmed that the most frequent mutation was homozygous M694V genotype. R202Q may be important in patients with FMF-associated AA amyloidosis. Thus, it is suggested that investigation of R202Q should be considered as a genetic test for Turkish FMF patients.

Sonographic assessment of spleen size in Turkish migrants with Familial Mediterranean fever in Germany.

OBJECTIVES: Familial Mediterranean fever (FMF) can be associated with splenomegaly. Prospective quantitative data are lacking. We performed a sonographic assessment of spleen size in patients with FMF and healthy control participants to assess its diagnostic value. METHODS: Patients with FMF according to the criteria of Livneh et al (Arthritis Rheum 1997; 40:1879-1885) who were in an asymptomatic interval and control participants were prospectively included in this study in Germany and underwent sonographic measurement of the spleen as well as a structured interview and a physical examination. Patients and controls were Turkish migrants. RESULTS: Thirty-six patients and 27 controls were included. Patients and controls did not differ significantly in age (mean ± SD, 34.8 ± 9.7 versus 33.3 ± 10.0 years, respectively; P = .56), sex, height, weight, or body mass index (26.7 ± 4.7 versus 26.1 ± 4.3 kg/m(2); P = .63). Spleen size was greater in patients than controls in width (4.3 ± 1.0 versus 3.7 ± 0.7 cm; P = .008) and also length (12.1 ± 1.9 versus 10.5 ± 1.4 cm; P = .001). Twenty-six of 36 patients (72.2%) had a history of appendectomy compared to 3 of 27 controls (11.1%; P < .001). The combination of an enlarged spleen (length >11 cm and/or width >4 cm) gave specificity of 100% (95% confidence interval, 87%-100%) and a positive predictive value of 100% (95% confidence interval, 78%-100%) for the diagnosis of FMF in our study. CONCLUSIONS: Spleen size as evaluated by sonography is larger in patients with FMF compared to healthy controls. Most patients with FMF included in this study had undergone appendectomy. Familial Mediterranean fever should be considered as a differential diagnosis in Turkish migrants in Germany if the spleen is enlarged and a history of appendectomy is reported.

Genotype-phenotype correlation in Japanese patients with familial Mediterranean fever: differences in genotype and clinical features between Japanese and Mediterranean populations.

INTRODUCTION: Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disease characterized by recurrent self-limiting fever and serositis that mainly affects Mediterranean populations. Many patients with FMF have been reported in Japan due to increasing recognition of this condition and the availability of genetic analysis for the gene responsible, MEFV. The present study was performed to elucidate the clinical characteristics of Japanese FMF patients and to examine the precise genotype-phenotype correlation in a large cohort of Japanese FMF patients. METHODS: We analyzed the MEFV genotypes and clinical manifestations in 116 patients clinically diagnosed as having FMF and with at least one mutation. RESULTS: The most frequent mutation in Japanese patients was E148Q (40.2%), followed by M694I (21.0%), L110P (18.8%), P369S (5.4%), and R408Q (5.4%). In contrast, common mutations seen in Mediterranean patients, such as M694V, V726A, and M680I, were not detected in this population. The clinical features with M694I were associated with more severe clinical course compared to those seen with E148Q. P369S/R408Q showed variable phenotypes with regard to both clinical manifestations and severity. Patients with M694I showed a very favorable response to colchicine therapy, while those with P369S and R408Q did not. CONCLUSIONS: Clinical features and efficacy of treatment in Japanese FMF patients vary widely according to the specific MEFV gene mutation, and therefore genetic analysis should be performed for diagnosis in cases of Japanese FMF.

Results from a multicentre international registry of familial Mediterranean fever: impact of environment on the expression of a monogenic disease in children.

BACKGROUND AND AIM: Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by mutations of the MEFV gene. We analyse the impact of ethnic, environmental and genetic factors on the severity of disease presentation in a large international registry. METHODS: Demographic, genetic and clinical data from validated paediatric FMF patients enrolled in the Eurofever registry were analysed. Three subgroups were considered: (i) patients living in the eastern Mediterranean countries; (ii) patients with an eastern Mediterranean ancestry living in western Europe; (iii) Caucasian patients living in western European countries. A score for disease severity at presentation was elaborated. RESULTS: Since November 2009, 346 FMF paediatric patients were enrolled in the Eurofever registry. The genetic and demographic features (ethnicity, age of onset, age at diagnosis) were similar among eastern Mediterranean patients whether they lived in their countries or western European countries. European patients had a lower frequency of the high penetrance M694V mutation and a significant delay of diagnosis (p<0.002). Patients living in eastern Mediterranean countries had a higher frequency of fever episodes/year and more frequent arthritis, pericarditis, chest pain, abdominal pain and vomiting compared to the other two groups. Multivariate analysis showed that the variables independently associated with severity of disease presentation were country of residence, presence of M694V mutation and positive family history. CONCLUSIONS: Eastern Mediterranean FMF patients have a milder disease phenotype once they migrate to Europe, reflecting the effect of environment on the expression of a monogenic disease.

Genotype-phenotype and genotype-origin correlations in children with mediterranean fever in Germany - an AID-net study.

Familial Mediterranean fever (FMF) is the most inherited common autoinflammatory disease (AID) with mutations in the MEFV (MEditerraneanFeVer) gene.The Mor- and Pras-Score modified for children and C-reactive protein (CRP) were used to assess FMF disease severity in Germany. We evaluate the applicability of the 2 severity scores and the correlations between ethnic origin, phenotype, and genotype.Among 242 children (median 5 age at diagnosis), we detected 431 pyrin mutations and 22 different sequence variants, including one new mutation (p.Gly488Asp). The 5 most -frequent alterations were p.Met694Val (55.2%), p.Met680lle (11.8%), p.Val726Ala (10%), p.Glu148Gln (7.9%) and p.Met694IIe (2.3%). The prevailing ancestries of 223 cases were Turkish (82.5%) and Lebanese (8.1%). Homozygous p.Met694Val substitution (30.2%) was associated with a more severe disease activity by Mor-Score, as well as with a higher mean CRP (74 mg/l) compared to patients with other mutations. Indeed, Mor- and Pras-Score were inconsistent with each other. A typical distribution of mutations in different ethnic populations was obvious, but not statistically verifiable due to the low number of cases.The homozygous p.Met694Val substitution was associated with a more severe disease activity in our German cohort. The common severity scores were inconsistent in -children.

Disease severity in adult patients of Turkish ancestry with familial mediterranean fever living in Germany or Turkey. Does the country of residence affect the course of the disease?

BACKGROUND: The environment may affect the course of familial Mediterranean fever (FMF). OBJECTIVE: The objective of this study was to compare disease severity between adult FMF patients in Turkey (TR) and Germany (G). METHODS: Adult FMF patients of Turkish ancestry on colchicine living in Turkey (n = 40) or G (n = 35) were compared. Disease severity, C-reactive protein (CRP), and erythrocyte sedimentation rate were assessed. RESULTS: Groups differed significantly in the following aspects: age at onset of disease (TR: 15.6, G: 10.8 years; P = 0.02), delay between onset and initiation of colchicine treatment (TR: 6.8 years, G: 14.9 years; P < 0.001), female gender (TR: 80%, G: 57.1%; P = 0.04), and duration of disease (TR: 14.4 years, G: 23.4 years; P < 0.001). There was no significant difference in colchicine treatment concerning average dosing and duration of therapy. No significant difference could be found between the 2 groups in CRP and disease severity as assessed by the score of Pras et al. (Am J Med Genet. 1998;75:216-219) even after adjusting for potential confounding variables. Mean erythrocyte sedimentation rate was significantly higher among patients living in G (TR: 13.2 mm/first hour, G: 26.3 mm/first hour; P < 0.001). Among patients living in Germany, there was a significant difference in age at FMF onset depending on their country of birth (born in TR: 14.9 years, born in G: 6.9 years; P = 0.0001). CONCLUSIONS: In adult FMF patients living in Turkey or Germany, no difference in disease activity or CRP could be found. German patients were younger at onset of disease and had a longer delay between onset and initiation of colchicine treatment.

Comparative screening of FMF mutations in various communities of the Israeli society.

Familial Mediterranean Fever (FMF) is an autosomal recessive disease that is widely spread in the populations of the Mediterranean region. It is characterized by recurrent fever and inflammatory attacks. A total of 1700 suspected patients, belonging to various communities in Israel: Jews (Ashkenazi and non-Ashkenazi), Arabs (Muslims and Christians) and Druze, was subjected to examination for FMF mutation screening. The patients were screened for the most common six MEFV gene mutations namely, M680I, M694V, M694I, V726A, E148Q and K695R. Fifty-five percent of the cases were confirmed to have MEFV mutations. The most common mutations among all the cases studied were M694V, E148Q and V726A. The common mutations in the respective communities were: among the Jews M694V with a frequency of 69.9% (76.8% for non-Ashkenazi Jews and 43.6% for Ashkenazi Jews), among the Arabs V726A with a frequency of 32.7% (32.7% for Muslims and 32.1% for Christians) and among Druze it was E148Q with a frequency of 52.1%. The characteristic mutation present in Jews was K695R and the one in Arabs was M680I, while no characteristic mutation was found in Druze. On the other hand, mutation E148Q was observed to have a considerable occurrence in patients of all ethnic groups studied. Furthermore, our results revealed that homozygous mutations accounted for 168 cases (18%). The homozygote mutation M694V was the most prevalent among Jews and the E148Q mutation was the most common among Druze, while, among Arabs there were three homozygous mutations having maximum prevalence, namely, V726A, M694V and M694I. Our study comprehensively provided a spectrum of FMF mutations in various communities of Israeli society.

Familial Mediterranean fever in Germany: clinical presentation and amyloidosis risk.

OBJECTIVE: To characterize patients with familial Mediterranean fever (FMF) with and without AA amyloidosis living in Germany. METHOD: Clinical and genetic data from 64 FMF patients were analysed for amyloidosis risk factors. RESULTS: Fifty-five patients (85%) were of Turkish or Armenian origin. Thirty-one patients (48%) developed FMF symptoms before the age of 16 years. Sixteen patients (26%) became symptomatic after age 20. Symptoms reported were peritonitis (95%), fever (78%), pleuritis (59%), arthralgia (60%), arthritis (32%), erysipelas-like erythema (23%), and vasculitis (8%). FMF diagnosis was delayed for a median of 8.0 years. Genetic analysis confirmed M694V as the most prevalent Mediterranean fever (MEFV) gene mutation in 46 out of 59 patients (78%). M694V homozygosity was associated with an earlier FMF onset (median age 5.5 years, p = 0.0001) and a higher prevalence of peritonitis (p = 0.007) and pleuritis (p = 0.0007) compared to patients without an M694V mutation. AA amyloidosis was detected in 16 patients (25%) at a median age of 36.5 years and tended to be associated with a higher age at disease onset (p = 0.062) and a higher FMF activity score (p = 0.093). AA amyloidosis was significantly associated with a higher age at FMF diagnosis (p = 0.0022). CONCLUSIONS: Clinical symptoms of FMF-affected migrants living in Germany resemble those observed in their home country. In particular, patients with an onset of FMF symptoms after age 20 and a later FMF diagnosis have a high risk of AA amyloidosis. Symptomatic patients who originate from countries with a higher FMF prevalence should be screened for FMF and proteinuria.

The M694V mutation in Armenian-Americans: a 10-year retrospective study of MEFV mutation testing for familial Mediterranean fever at UCLA.

Familial Mediterranean fever (FMF), inherited in an autosomal recessive manner, is a systemic auto-inflammatory disorder characterized by recurrent attacks of fever with peritonitis, pleuritis, synovitis and erysipeloid rash. The marenostrin-encoding fever (MEFV) gene, located on chromosome 16p13.3, is the only gene in which mutations are currently known to cause FMF. To correlate specific genotypes with adverse phenotypes of affected populations residing in the Western United States, a retrospective case series review was conducted of all MEFV gene mutation testing completed at UCLA Clinical Molecular Diagnostic Laboratory between February 2002 and February 2012, followed by clinical chart review of all subjects who either have a single or double mutation. All 12 common mutations in the MEFV gene were analyzed and the M694V variant was found to be associated with an adverse FMF clinical outcome in the Armenian-American population, manifested by earlier onset of disease, increased severity of disease, and renal amyloidosis.

Familial Mediterranean fever in Germany: epidemiological, clinical, and genetic characteristics of a pediatric population.

UNLABELLED: Familial Mediterranean fever (FMF) is an autoinflammatory disease and belongs to the heterogeneous group of hereditary recurrent fever syndromes (HRFs). AIMS: The aims of the study were to determine the incidence of FMF in Germany and to describe the spectrum of pyrin mutations and the clinical characteristics in children. A prospective surveillance of children with HRF including FMF was conducted in Germany during a time period of 3 years by the German paediatric surveillance unit for rare paediatric diseases (ESPED). Monthly inquiries were sent to 370 children's hospitals (Clinic-ESPED, n1) and to 23 laboratories (Laboratory-ESPED, n2). Inclusion criteria were children ≤ 16 years of age, disease-associated pyrin mutations, and more than three self-limiting episodes of fever >38.5 °C with increased inflammation markers. In n1, 122 patients with FMF and 225 pyrin mutations were identified. Ninety-two of 122 (75 %) children were of Turkish origin. The minimum incidence of FMF was estimated to be 3 (95 % CI: 2.48-3.54) per 10(6) person-years in the whole children population and 55 (95 % CI: 46-66) per 10(6) person-years in Turkish children living in Germany. N1 U n2 amounted to 593 asymptomatic and symptomatic carriers of 895 mutations (overlap of 73 cases with 134 mutations). p.Met694Val (45 %), p.Met680Ile (14 %), p.Val726Ala (12 %), and p.Glu148Gln (11.5 %) were the most common pyrin mutations. CONCLUSIONS: Despite FMF being the most frequent of the HRFs, its incidence in Germany is low. Twenty-five to 50 FMF patients ≤ 16 years are newly diagnosed per year. The disease is most commonly observed in individuals of Turkish ancestry.