The Clinical Journey of a Patient with Familial Mediterranean Fever: One Gene, Three Diseases

Introduction Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease characterized by recurrent self-limiting attacks of fever and serositis (Ben-Chetrit E and Levy M, Lancet 1998; 351: 659–664). The gain-of-function mutations in the responsible gene encoding pyrin, known as the MEditerranean FeVer (MEFV) gene, cause a reduction in the activation threshold of pyrin inflammasome triggering recurrent clinical attacks, subclinical inflammation, and a tendency for other inflammatory diseases (Jamilloux Y et al., Rheumatology (Oxford) 2018; 57: 100–111). Familial Mediterranean fever is more prevalently seen in the Middle Eastern communities. A relatively severe disease phenotype together with several diseases associated with FMF was frequently reported around this part of the world (Ben-Chetrit E and Yazici H, Clinical and Experimental Rheumatology 2019; 37 (Suppl 121): 18–22). A large spectrum of FMF-associated diseases ranging from inflammatory arthritis and vasculitis to inflammatory bowel disease (IBD) may cause an evolving clinical phenotype that pose a diagnostic and therapeutic conundrum for clinicians involved in the management of these patients. Additionally, the diagnosis of FMF or the presence of MEFV gene mutations can affect the clinical features and severity of these associated diseases (Avar Aydin PO, et al. Clinical and Experimental Rheumatology 2020; 38 (Suppl 127): 112–117; Ayaz NA, et al. Rheumatology International 2021; 41: 113–120; Ozcakar ZB, et al. Journal of Rheumatology 2008; 35: 2427–2429). Herein, we describe a nearly 10-year follow-up of a pediatric case with FMF who presented with very early-onset inflammatory bowel disease (VEO-IBD) and developed a persistent multifocal form of chronic nonbacterial osteomyelitis (CNO). A part of the case presentation has been previously reported in an original study discussing the relation of CNO and MEFV gene mutations (Avar Aydin PO, et al. Clinical and Experimental Rheumatology 2020; 38 (Suppl 127): 112–117). The aim to describe the case here is to add a more detailed discussion to underline a severe disease phenotype of FMF, its modifying effect on associated diseases, and the need for various therapeutic agents to control disease activity. Publication History Article published online: 17 March 2023 © 2023. Thieme. All rights reserved. Georg Thieme Verlag Rüdigerstraße 14, 70469 Stuttgart, Germany