Open AccessA novel mutation of IL1RN in the deficiency of interleukin‐1 receptor antagonist syndrome: Description of two unrelated cases from Brazil
Author(s) -
Jesus Adriana A.,
Osman Mazen,
Silva Clovis A.,
Kim Peter W.,
Pham TuyetHang,
Gadina Massimo,
Yang Barbara,
Bertola Débora R.,
CarneiroSampaio Magda,
Ferguson Polly J.,
Renshaw Blair R.,
Schooley Ken,
Brown Michael,
AlDosari Asma,
AlAlami Jamil,
Sims John E.,
GoldbachMansky Raphaela,
ElShanti Hatem
Publication year - 2011
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/art.30588
Subject(s) - medicine , immunology , interleukin 1 receptor antagonist , autoantibody , inflammation , mutation , receptor antagonist , gene , biology , genetics , receptor , antibody , antagonist
Objective Monogenic autoinflammatory diseases are disorders of Mendelian inheritance that are characterized by mutations in genes that regulate innate immunity and whose typical features are systemic inflammation without high‐titer autoantibodies or antigen‐specific T cells. Skin and bone inflammation in the newborn period have been described in 3 of these autoinflammatory disorders: neonatal‐onset multisystem inflammatory disease, Majeed syndrome, and deficiency of interleukin‐1 (IL‐1) receptor antagonist (DIRA) syndrome. This study was undertaken to present the characteristics of the DIRA syndrome in 2 cases from Brazil, and describe a novel mutation in IL1RN . Methods Two unrelated Brazilian patients were evaluated for the clinical signs and symptoms of these 3 disorders, and peripheral blood samples were assessed for mutations in NLRP3 , LPIN2 , and IL1RN by DNA resequencing analysis. A mutation in IL1RN that encodes a mutant protein was identified, and the expression and function of this mutant protein were compared to those of the wild‐type protein. Results Both patients presented with pustular dermatitis resembling generalized pustular psoriasis, recurrent multifocal aseptic osteomyelitis, and elevation in the levels of acute‐phase reactants, all of which are features most consistent with the DIRA syndrome. Chronic lung disease was observed in 1 of the patients, and jugular venous thrombosis was observed in the other patient. Both patients showed a partial response to corticosteroid therapy, and 1 patient experienced an initial improvement of dermatitis with the use of acitretin. Both patients were homozygous for a novel 15‐bp (in‐frame) deletion on the IL1RN gene. The mutated protein expressed in vitro had no affinity with the IL‐1 receptor, and stimulation of the patients' cells with recombinant human IL‐1α or IL‐1β led to oversecretion of proinflammatory cytokines, similar to the findings obtained in previously reported patients. Conclusion The presence of the same homozygous novel mutation in IL1RN in 2 unrelated Brazilian patients suggests that this genetic variant may be a founder mutation that has been introduced in the Brazilian population.