AN ATYPICAL PRESENTATION OF FAMILIAL MEDITERRANEAN FEVER

Abstract

<h3>Introduction</h3> Familial Mediterranean Fever(FMF) is thought to be autosomal recessive disease characterized by periodic fevers associated with serositis. In this case we present a patient with FMF with only one mutation in MEFV gene, suggesting a more variable penetrance of the FMF phenotype. <h3>Case Description</h3> An 8-year-old female diagnosed with juvenile idiopathic arthritis and asymptomatic hematuria presented for elevated immunoglobulins and inflammatory markers. She had no history of recurrent/severe infections or fevers. She endorsed monoarticular joint pains and abdominal pains. Family history was significant for a 1-year-old sister diagnosed with PFAPA and a 15-months-old brother who died from human metapneumovirus associated pulmonary hemorrhage. On exam, she appeared well-nourished, no rash/oral ulcers/abdominal tenderness. Labs were significant for CRP-54, ESR-52, IgG-1950, IgA-327, IgM-230. Urinalysis had 3+ blood without proteinuria. Taken together, her history raised concern for monogenic inborn error of immunity and a primary immunodeficiency panel was sent. Her panel revealed a heterozygous pathogenic variance of MEFV(V726A) responsible for FMF. Her father was later also diagnosed with FMF responsive to colchicine with the same pathogenic MEFV variant. Her cytokines were elevated, including IL-1B, and she was subsequently started on colchicine 0.6mg BID and canakinumab 75mg q4-weeks. Following treatment, she had normalization of inflammatory markers (Table 1) and resolution of joint pains. <h3>Discussion</h3> This case highlights the existence of a subset of FMF patients who have only one mutation in the MEFV gene. Broadening our understanding of the complex genetics and variable penetrance of FMF can prevent delays in diagnosis and treatment.