Comprehensive analysis of mutations in the MEFV gene reveal that the location and not the substitution type determines symptom severity in FMF

Epigenetic, transcriptional, and functional characterization of myeloid cells in familial Mediterranean fever

Familial Mediterranean fever (FMF) is a periodic fever syndrome caused by variation in MEFV. FMF is known for IL-1β dysregulation, but the innate immune landscape of this disease has not been comprehensively described. Therefore, we studied circulating inflammatory proteins, and the function of monocytes and (albeit less extensively) neutrophils in treated FMF patients in remission. We found that monocyte IL-1β and IL-6 production was enhanced upon stimulation, in concordance with alterations in the plasma inflammatory proteome. We did not observe changes in neutrophil functional assays. Subtle differences in chromatin accessibility and transcriptomics in our small patient cohort further argued for monocyte dysregulation. Together, these observations suggest that the MEFV-mutation-mediated primary immune dysregulation in monocytes leads to chronic inflammation that is subsequently associated with counterregulatory epigenetic/transcriptional changes reminiscent of tolerance. These data increase our understanding of the innate immune changes in FMF, aiding future management of chronic inflammation in these patients.

Serum Asprosin Level as a New Biomarker in Differentiating Familial Mediterranean Fever Attacks

Introduction Familial Mediterranean fever (FMF) is a recessively inherited disease characterized by recurrent attacks of fever and sterile polyserositis. Recently, some proteins originating from adipose tissue have been demonstrated to play a critical role in the inflammatory process. Asprosin is a new adipokine secreted by adipose tissue, and proinflammatory cytokines have been determined to increase with the decrease of circulating asprosin. This study was designed to evaluate the level of asprosin in the acute attack and attack-free period in FMF patients. Materials and methods A total of 65 FMF patients were evaluated for this cross-sectional case-control study. Those who were obese and had concomitant diabetes mellitus, hypertension, heart failure, and rheumatological disease were excluded from the study. The patients were divided into two groups: attack-free period and attack period. Fifteen healthy individuals who were not obese and had no additional disease were included as the control group. Demographic data, gene analyses, laboratory findings, and symptoms were recorded at the time of diagnosis. Serum asprosin level was studied by enzyme-linked immunosorbent assay test in the outpatient clinic controls of the patients. Asprosin levels and other laboratory findings were compared between the attack, attack-free, and control groups. Results Of the patients included in the study, 50% were in the attack period, and 50% were in the free-attack period. The mean age of the FMF patients was 34±10 years. Asprosin level in the control [median (interquartile range (IQR))=30.4 (21.5-57.7) ng/mL] group was significantly higher than the attack [median (IQR)=21.5 (17.5-28) ng/mL] and attack-free [median (IQR)=19(18.7-23) ng/mL] groups (p=0.001). C-reactive protein and sedimentation levels were significantly higher in the attack group compared to the other two groups (p<0.001). There was a moderate correlation between C-reactive protein and asprosin levels (Ro=-0.314, p=0.01). The cut-off value of serum asprosin level was determined as 21.6 ng/mL; sensitivity was 78%, and specificity was 77% (p<0.001). Conclusion The study demonstrated that the serum asprosin levels of FMF patients with acute attack were lower than those in the attack-free periods and healthy controls. Asprosin is likely to have a role in the anti-inflammatory cascade.

Determining the origin of different variants associated with familial mediterranean fever by machine-learning

A growing number of familial Mediterranean fever (FMF) patients in Israel do not have a single country of origin for all four grandparents. We aimed to predict the Mediterranean fever gene (MEFV) variant most likely to be found for an individual FMF patient, by a machine learning approach. This study was conducted at the Sheba Medical Center, a referral center for FMF in Israel. All Jewish referrals included in this study carried an FMF associated variant in MEFV as shown by genetic testing performed between 2001 and 2017. We introduced the term 'origin score' to capture the dose and different combinations of the grandparents' origin. A machine learning approach was used to analyze the data. In a total of 1781 referrals included in this study, the p.Met694Val variant was the most common, and the variants p.Glu148Gln and p.Val726Ala second and third most common, respectively. Of 26 countries of origin analyzed, those that increased the likelihood of a referral to carry specific variants were identified in North Africa for p.Met694Val, Europe for p.Val726Ala, and west Asia for p.Glu148Gln. Fourteen of the studied countries did not show a highly probable variant. Based on our results, it is possible to describe an association between modern day origins of the three most common MEFV variant types and a geographical region. A strong geographic association could arise from positive selection of a specific MEFV variant conferring resistance to endemic infectious agents.

Whole-genome sequencing of 1,171 elderly admixed individuals from São Paulo, Brazil

As whole-genome sequencing (WGS) becomes the gold standard tool for studying population genomics and medical applications, data on diverse non-European and admixed individuals are still scarce. Here, we present a high-coverage WGS dataset of 1,171 highly admixed elderly Brazilians from a census-based cohort, providing over 76 million variants, of which ~2 million are absent from large public databases. WGS enables identification of ~2,000 previously undescribed mobile element insertions without previous description, nearly 5 Mb of genomic segments absent from the human genome reference, and over 140 alleles from HLA genes absent from public resources. We reclassify and curate pathogenicity assertions for nearly four hundred variants in genes associated with dominantly-inherited Mendelian disorders and calculate the incidence for selected recessive disorders, demonstrating the clinical usefulness of the present study. Finally, we observe that whole-genome and HLA imputation could be significantly improved compared to available datasets since rare variation represents the largest proportion of input from WGS. These results demonstrate that even smaller sample sizes of underrepresented populations bring relevant data for genomic studies, especially when exploring analyses allowed only by WGS.

Whole genome sequencing (WGS) data on non-European and admixed individuals remains scarce. Here, the authors analyse WGS data from 1,171 admixed elderly Brazilians from a census cohort, characterising population-specific genetic variation and exploring the clinical utility of this expanded dataset.

Atypical Autosomal-Dominant Inheritance of Familial Mediterranean Fever

Familial Mediterranean fever (FMF) was previously believed to be an autosomal recessive disease. We present a patient with only one pathogenic variation of the MEFV gene due to the c.2177T>C mutation. The patient had clinical features of recurrent fevers and abdominal pain, serositis, and a history of multiple abdominal surgeries for pain. He was eventually diagnosed with FMF. This case report demonstrates an example of the rare autosomal-dominant phenotype of FMF.

Clinical significance of MEFV gene variation R202Q

BACKGROUND

The aim of this study was to evaluate the phenotypic features and the clinical significance of the R202Q mutation of the MEFV gene.

METHODS

We retrospectively reviewed the medical records of Familial Mediterranean Fever patients with M694V/- and M694V/R202Q mutations. We compared the patients regarding disease severity, symptoms, age at the onset of symptoms, gender, consanguinity, and family history.

RESULTS

Twenty-one patients (9 males, 12 females) had compound heterozygote mutation (M694V/R202Q), and 37 patients (23 males, 14 females) had M694V/- mutation. The mean age of the patients at the time of diagnosis was 7.3 ± 4.3 and 9.2 ± 3.7 years. The rate of arthritis was significantly higher in patients with M694V/R202Q heterozygote mutation than those with M694V/- heterozygote mutation (76.2% vs 32.4%; p =  < 0.001). The mean severity score was higher in M694V/R202Q heterozygote group although it did not reach statistical significance (8.43 ± 1.69 vs 7.49 ± 1.50; p = 0.082). However, the rate of having a high severity score was significantly higher in the M694V/R202Q mutation group than in the other group (47.6% vs 21.6%, respectively; p = 0.039). The rate of arthritis was significantly higher in patients with M694V/R202Q heterozygote mutation than those with M694V/- heterozygote mutation (76.2% vs 32.4%; p =  < 0.001).

CONCLUSION

Our finding supports the possibility that R202Q may be pathogenic rather than a variation. We found that the R202Q mutation is associated with the inflammatory phenotype of FMF; hence, the typical clinical findings of FMF especially arthritis can be observed in patients with compound mutation including R202Q. Key Points • We found that the R202Q mutation is associated with the inflammatory phenotype of FMF • The patients with the R202Q mutation had a greater rate of arthritis symptoms.

MEFV E148Q variant is more associated with familial Mediterranean fever when combined with other non-exon 10 MEFV variants in Japanese patients with recurrent fever

OBJECTIVE

To investigate the genetic characteristics of one of the MEFV gene variants, p.Glu148Gln (E148Q), in patients with familial Mediterranean fever (FMF) and examine its significance in Japanese patients with recurrent fever.

METHODS

The clinical phenotype and genomic variants of systemic autoinflammatory diseases (SAIDs), including MEFV, were analyzed in 211 Japanese patients with recurrent fever. Genetic analysis was performed via next-generation sequencing of exons, including exon-intron boundaries.

RESULTS

Twelve patients met the diagnostic criteria for SAIDs other than FMF. Considering 199 patients with recurrent fever, 137 cases (68.8%) were clinically diagnosed with FMF. Although Bonferroni-adjusted p-value did not reach significance level, the group containing heterozygous E148Q and other variants tended to be at higher risk of developing the FMF phenotype (nominal p = .036) than the group with heterozygous E148Q only. Comparison between the group with heterozygous E148Q and other variants and the heterozygous group containing non-E148Q showed no statistically significant difference in FMF phenotype expression (nominal p = 1.00).

CONCLUSION

Patients with heterozygous E148Q and other variants exhibited higher expression of FMF phenotype than those with heterozygous E148Q only, and suggested that other variants than E148Q as well as exon 10 variants might contribute to the FMF phenotype.

Familial Mediterranean fever: breaking all the (genetic) rules

OBJECTIVE

FMF is an inherited autoinflammatory syndrome, characterized by attacks of painful periodic fever caused by diffuse serositis and risk of secondary amyloidosis due to IL-1β-mediated inflammation. The disease appears to be transmitted through autosomal recessive mutations in the MEFV gene encoding the pyrin protein Although more than 300 variants have been reported worldwide so far, their association with symptom severity, the relative frequencies in different populations and the disease penetrance are far from being completely understood. We investigated genotype-phenotype correlations in two large nuclear families and verified whether commonly used web-based tools can usefully predict variant pathogenicity in FMF.

METHODS

Peripheral blood samples were obtained from 15 patients of two families who had been diagnosed with FMF according to international criteria. The entire MEFV coding region was sequenced in all subjects, and 179 MEFV variants were surveyed with five different pathogenicity predictors.

RESULTS

The inheritance of FMF could not be explained by traditional autosomal recessivity in both families. In silico tools demonstrated a significant association of variants' pathogenicity with their position along the coding sequence but not with variants' frequency.

CONCLUSION

By describing two large families with paradigmatic complexity of FMF genetics, we conclude that established concepts in assessing the causative role of variants identified in mutation screening cannot be easily translated into appropriate genetic counselling in FMF. Furthermore, we demonstrate that variants frequently associated with severe disease are not predicted to significantly impact protein function using in silico algorithms.

Familial Mediterranean Fever in Chinese Children: A Case Series

Background: Familial Mediterranean fever (FMF) is an inherited auto-inflammatory disorder and is extremely rare in Chinese. This study aimed to investigate the demographic, clinical, and genetic features of FMF in a series of Chinese pediatric patients. Methods: This was a retrospective case series of children with recurrent febrile or inflammatory episodes and referred to the Peking Union Medical College Hospital between 06/2013 and 06/2018. All suspected patients were genetically diagnosed and met the Tel-Hashomer criteria for FMF. Demographic, clinical, genetic, and treatment characteristics were collected. Descriptive statistics were used. Results: Eleven patients were included (seven boys and four girls). The median age at the time of disease onset was 7.1 (range, 3-12) years, while the median age at diagnosis was 10.9 (range, 6-15) years. The median delay in diagnosis was 2.1 years (range, 6 months to 6.7 years). Fever (100%, 11/11) was the most common symptom, followed by joint pain (63.6%, 7/11), rash (54.5%, 6/11), abdominal pain (36.4%, 4/11), and oral ulcers (18.2%, 2/11), without evidence of amyloidosis. C-reactive protein (81.8%, 9/11) and erythrocyte sedimentation (90.9%, 10/11) were increased during attacks. All patients harbored one to five different MEFV mutations, with E148Q and L110P being the most frequent. A novel non-synonymous mutation F636Y in exon 10 was discovered. Favorable responses to colchicine was observed in all six treated patients. Conclusion: The most common variants in our study were E148Q and L110P. F636Y may found for the first time. Colchicine led to favorable responses in all treated patients.

Clinical and Demographic Evaluation According to MEFV Genes in Patients with Familial Mediterranean Fever

The present study examined the relationship between clinical findings and mutation analyses in children with Familial Mediterranean Fever (FMF) in the inner Black Sea region of Turkey. This retrospective, cross-sectional study included patients with FMF who were evaluated between 2007 and 2015. FMF was diagnosed according to the Tel Hashomer criteria. FMF mutations were analyzed using a Real-time PCR System (Roche Diagnostics, Mannheim, Germany), and patients were classified into three groups according to allele status. The most common symptom was abdominal pain (99%, n = 197). The most frequent mutations were M694V and R202Q. Chest pain was reported more often in patients homozygous for M694V (61.4%). Although fever, abdominal pain, and arthritis were more commonly observed with the M694V mutation, chest pain was the most common symptom in R202Q carriers (n = 10, 32.3%). Proteinuria was observed in 42 (21.2%) patients, frequently accompanied by the M694V mutation (28.6%). The most common mutations in children with FMF in Turkey were M694V and R202Q. Recurrent abdominal pain and arthritis/arthralgia were commonly observed in patients with M694V and R202Q mutations. Moreover, chest pain was commonly seen with the R202Q mutation. Thus, R202Q might be a disease-causing mutation in FMF patients.

Comprehensive analysis of mutations in the MEFV gene reveal that the location and not the substitution type determines symptom severity in FMF

Background

Familial Mediterranean Fever (FMF) is an autoinflammatory disorder caused by mutations in the MEFV gene. These mutations appear in different populations with different frequencies and their caused symptom severities vary from mild to moderate to severe depending on the mutation type.

Methods

In this study, we analyzed the mutations that have been reported in the MEFV gene from symptomatic FMF patients and compared their frequencies in different populations from the 1000 Genome and the Exome databases, using statistical clustering. We also analyzed the nucleotide and amino acid substitution patterns across the MEFV gene.

Results

We found 16 (8%) nonsynonymous mutations outside exon 10 that did not cluster with known disease‐causing mutations (DCMs), due to their high frequencies in other populations. We also studied the substitution patterns for nucleotides and amino acids to determine the conserved and variable regions in the MEFV gene. In general more nonsynonymous substitutions were reported in exons 2, 3, and 10 from the FMF database (symptomatic FMF patients) compared to the 1000 Genome and the Exome databases. The same was true for amino acid (AA) substitutions where there were 1.5 times more radical (RAD) to conservative (CON) changes. However, when it came to AA substitutions exon 10 was quite conserved with a RAD/CON ratio of 0.9. In fact, we report that the most severe FMF symptoms are caused by conservative mutations in two highly conserved exon 10 regions.

Conclusion

We found presumptive FMF‐causing mutations that did not cluster with DCMs based on their allele frequencies. We also observed that the type of mutation is less likely to determine the severity of the FMF symptoms; rather it was the location of the mutations that was the determining factor.