AB0727 STUDY OF MEFV GENE MUTATIONS IN A COHORT OF CHILDREN: A SINGLE CENTER

Background:Familial Mediterranean fever (FMF) is a monogenic autoinflammatory hereditary disease characterized by recurrent episodes of fever with sterile peritonitis, pleural inflammation, arthritis, and/or erysipelas-like rash. Among all variants of the MEFV gene, according to the literature, five pathogenic ones have been identified, which in 75% of cases lead to the development of a typical clinical presentation: V726A, M694V, M694I, M680I, and E148Q. Among them, the M694V variant is the most common and occurs in patients with FMF in 20-65% of cases. At the same time, approximately 10 to 20% of patients meeting the diagnostic criteria for FMF do not have pathogenic variants in the MEFV gene. Despite the fact that the molecular genetic, pathogenetic and clinical features of the disease have been studied detailed, the diagnosis remains difficult due to the lack of a clear correlation between the patient’s clinical and genetic data.Objectives:To analyze the obtained genetic data of patients with pathogenic variants in the MEFV gene.Methods:The study included 103 patients who are mainly observed at the rheumatology department of the National Medical Research Center of Children’s Health of Ministry of Health of the Russian Federation in Moscow. All patients underwent analysis of the MEFV gene using Sanger sequencing with further statistical processing of the data obtained.Results:Of 103 patients, the pathogenic variant of the MEFV gene was found in 93 patients (90.3%), in 10 patients (9.7%) - the pathogenicity of the revealed variant was contradictory. Of 93 patients with the pathogenic variant of MEFV, the clinical presentation of the disease fits to FMF in 37 patients (39.6%). 11 (29.7%) of them had a mutation in M694V. Out of 37 children who met the criteria for FMF diagnosis, 15 (40.5%) children had a homozygous pathogenic variant of MEVF, and 22 (59.5%) children had two mutations in a heterozygous state. 57 patients who do not have a typical clinical presentation, which is specifical for FMF are observed at the departments of rheumatology, cardiology and nephrology, 13 patients are on an outpatient observation, and 6 patients at the time of the study are over 18 years old. 8 (14%) of them had a mutation in M694V. Among 57 patients with pathogenic heterozygous variants in a, 22 patients (38.6%) are observed in the rheumatology department, among them:• Enthesitis-related arthritis - 2 patients (9%);• Systemic juvenile arthritis - 13 patients (59%);• Oligoarthritis - 5 patients (23%);• Polyarthritis- 2 patients (9%).Conclusion:Analysis of the obtained data showed that FMF is characterized by a combination of the clinical presentation and the pathogenic variant in the MEFV gene. However, the disease manifests itself not only in the homozygous pathogenic variant, but also in the combination of two mutations in heterozygous. The presence of one heterozygous mutation, generally, does not lead to the development of FMF.References:[1]Konstantopoulos, A. Kanta, C. Deltas, V. Atamian, D. Mavrogianni, A.G. Tzioufas, I. Kollainis, K. Ritis, H.M. Moutsopoulos, Familial Mediterranean fever associated pyrin mutations in Greece Ann. Rheum. Dis., 62 (2003), pp. 479-481, 10.1136/ard.62.5.479.[2]Gershoni-Baruch R, Brik R, Zacks N, Shinawi M, Lidar M, Livneh A: The contribution of genotypes at the MEFV and SAA1 loci to amyloidosis and disease severity in patients with Mediterranean Fever,Seminars in Arthritis and Rheumatism,Volume 43, Issue 3, 2013, Pages 387-391familial Mediterranean fever. Arthritis Rheum 2003; 48: 1149–1155.[3]Booty MG, Chae JJ, Masters SL, et al. Familial Mediterranean fever with a single MEFV mutation: where is the second hit? Arthritis Rheum 2009; 60:185.Disclosure of Interests:None declared