Systemic autoinflammatory diseases (SAIDs) are a set of rare clinically and genetically heterogeneous conditions. The project proposes to identify novel genes and specific signatures in subgroups of patients with SAIDs.

SAIDs are characterized by long dormant periods with no or only minor clinical symptoms interrupted by febrile crises accompanied by serous and synovial membrane inflammation that spontaneously resolves. Over the last decades, more than 50 genes encoding key components of the innate immune system have been identified to be involved in the pathophysiology of SAIDs, with both germline and somatic mosaic variations. When disease-causing variations are identified, specific biotherapies are proposed depending on the involved gene and pathway. However, despite these scientific advances, most SAIDs (70%) are of unknown etiology, the diagnosis is made with significant delay, and no targeted therapy can be suggested. This project aims to generate specific understanding and develop strategies for SAID patients with unknown etiology. The investigators aim to advance our understanding of SAIDs pathophysiology, find the disease-causing gene variations and identify the involved cellular pathways that should accelerate correct diagnosis and personalize treatment.

Inclusion Criteria:

• A patient presenting with a clinical and biological aseptic inflammatory syndrome associating one or more of the following signs: spontaneously resolving fever, abdominal (pain, diarrhea), locomotor (arthralgia, myalgia), thoracic (pain, pericarditis), cutaneous, sensory (uveitis, deafness), or renal (amyloidosis) involvement.

Exclusion Criteria:

• Adult subject to legal protection measures (guardianship, curatorship, safeguard of justice).

Participants in this research will be recruited during a follow-up consultation for their condition.