Differential mutational profiles of familial Mediterranean fever in North Africa

R202Q prevalence in clinically diagnosed Familial Mediterranean Fever patients: 9 years of data analysis from 1570 patients living Central Black Sea region, Turkey

INTRODUCTION

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent self-limiting fever, peritonitis, arthritis, and erysipelas-like-erythema, common among ethnic groups such as Turkish, Armenian, Arab, and Jewish. The disease is caused by mutations in the MEFV gene encoding the Pyrin. This study examines the genotypes of FMF patients from Amasya, Turkey.

METHOD

According to the Tel Hashomer criteria, one thousand five hundred seventy patients (871 female, 699 male, mean age 21.2 ± 15.5 years) living in Amasya Province and the surroundings were screened for sequence variants in the entire MEFV gene. Besides, mutation types and alleles were evaluated with clinical findings.

RESULTS

MEFV mutations and polymorphisms were found in 1413 of the 1570 patients (90%). Among these patients, 5 (0.3%) were double homozygous, 152 (9.7%) were homozygous, 373 (23.8%) were double heterozygous, and 882 (56.2%) were heterozygous. The most frequent genotype was R202Q (960, 43.5%) followed by M694V (n = 412, 18.7%), E148Q (n = 321, 14.6%), and M680I (n = 200, 9.1%). The most common clinical symptoms were abdominal pain (96.4%) and fever (91.3%).

CONCLUSIONS

The fact that the R202Q genotype, which is compatible with the known FMF clinic, is frequently seen shows that it should be included in routine molecular screenings of the patients. Functional studies of the R202Q variant pyrin protein should be performed to understand FMF better. Finally, it is unclear whether the R202Q genotype might be regarded as a mutation while being approved as a polymorphism in the inFevers database.

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.

Case Report: A Pediatric Case of Familial Mediterranean Fever Concurrent With Autoimmune Hepatitis

Familial Mediterranean fever (FMF) is a hereditary, autoinflammatory disease that causes recurrent fever, arthritis, and serositis. The diagnosis of FMF is based on the presentation of typical clinical symptoms and the Mediterranean fever gene (MEFV) test. However, the challenge lies in diagnosing atypical cases. In this report, we have described a pediatric patient with complex FMF whose diagnosis required trio-whole exome sequencing (WES) and functional validation of a rare MEFV variant. A 3-year-old boy presented with recurrent episodes of elevated liver enzymes and arthralgia. He was diagnosed with autoimmune hepatitis (AIH), and his liver enzymes improved rapidly with steroid treatment. However, he exhibited recurrent arthralgia and severe abdominal attacks. Trio-WES identified compound heterozygous mutations in MEFV (V726A and I692del). Ex vivo functional assays of the patient’s monocytes and macrophages, which had been pre-treated with Clostridium difficile toxin A (TcdA) and colchicine, were comparable to those of typical FMF patients, thereby confirming the diagnosis of FMF. Although he was intolerant to colchicine because of liver toxicity, subsequent administration of canakinumab successfully ameliorated his abdominal attacks. However, it was ineffective against liver injury, which recurred after steroid tapering. Therefore, in this case, the pathogenesis of AIH was probably interleukin-1β (IL-1β)-independent. In fact, AIH might have been a concurrent disease with FMF, rather than being one of its complications. Nevertheless, further studies are necessary to determine whether FMF-induced inflammasome activation contributes to AIH development. Moreover, we must consider the possibility of mixed phenotypes in such atypical patients who present distinct pathologies simultaneously.

Spectrum of MEFV gene mutations in 4,256 familial Mediterranean fever patients from Iran: a comprehensive systematic review

Background

Familial Mediterranean fever (FMF), known as a disease with a high prevalence rate among Armenian, Turkish, Jewish, and Arab descent populations, occurs as a result of pathogenic variants in mediterranean fever (MEFV) gene. The aim of this study was to review the spectrum and frequency of MEFV gene mutations reported among Iranian FMF patients.

Methods

After performing a systematic review of the literature and implementation of inclusion and exclusion criteria, 16 articles published between 2004 and 2020, involving 4,256 Iranian FMF patients, were included.

Results

A total of 38 different MEFV gene mutations were identified. The most common mutations among Iranian FMF patients were: p.M694V (c.2080A > G) (20.27%), p.E148Q (c.442G > C) (10.27%), p.V726A (c.2177T > C) (8.24%), p.M680I (both c.2040G > C and c.2040G > A) (7.20%), p.R761H (c.2282G > A) (2.1%), and p.M694I (c.2082G > A) (2. 1%). The frequencies of these mutations were significantly different in different parts of the country.

Conclusions

The ranks and frequencies of p.M694V, p.E148Q, p.V726A, p.M680I, and p.M694I in our population were closer to those observed in the Mediterranean countries, especially in the Middle Eastern Arab populations. Although some comprehensive studies have been performed on Azeri Turkish patients living in northwestern Iran, studies in other areas, especially in eastern Iran, have been very limited. One reason for this observation could be due to the low frequency of FMF patients in those areas. Regardless of the reason for this, the exact spectrum and frequency of MEFV gene mutations in Iranian FMF patients remain unclear. Therefore, comprehensive future studies in different parts of the country are recommended.