- Behçet syndrome (BS) represents a chronic, relapsing, multisystem, autoinflammatory disorder.
- Precise etiology remains incompletely understood; strong but diverse genetic component
- Clinical manifestations are driven by hyperactive innate and adaptive immune responses, resulting in a highly variable presentation and potential involvement of any organ system.
- Variable clinical manifestations:
- Classic description of “triple symptom complex”: oral and genital mucocutaneous ulceration + ocular involvement (primarily panuveitis and retinal vasculitis)
- Other frequent symptoms include papulopustular cutaneous lesions, gastrointestinal (GI) pain, arthritis, and vascular involvement.
- Three distinct clinical subtypes with different expression profiles and disease pathways (1):
- Mucocutaneous BS (only cutaneous)
- Ocular BS (any involvement)
- Vascular BS (large vein thrombosis)
- Note: oral ulcers present in all subtypes
- Synonym(s): Behçet disease; Behçet triad; mucocutaneous ocular syndrome; Franceschetti-Valero syndrome; Adamantiades syndrome; Morbus Behçet; or Silk Road disease
- Predominant age: 20 to 40 years old; rare in pediatric and geriatric populations
- Predominant gender: female > male in United States, with males affected more severely, especially in the Middle East and Central Asia
- Rare in the United States, Northern Europe, and sub-Saharan Africa; endemic in Japan, the Middle East, and the Mediterranean region; more prevalent in the region of the ancient Silk Road, linking China to Italy
- 5.2/100,000 population in the United States
- 20 to 421/100,000 in Turkey
Etiology and Pathophysiology
Complex and diverse genetic and epigenetic basis, with precise etiology unknown. Multiple implicated factors including HLA-B genes (especially B51), high production of tumor necrosis factor (TNF) and IL-8, low production of IL-10, and polymorphisms in chemokines and adhesion factors. Common bacteria (streptococci) and viruses (herpes simplex virus [HSV]) appear to have a role in triggering immune responses, particularly from neutrophils and γδ T lymphocytes. Increased IL-12 drives Th1 response, targeting heat shock proteins (due to homology with streptococci, producing various autoantibodies, and inducing endothelial injury [likely responsible for prothrombotic state]) (1,2,3).
Familial clustering and earlier onset in successive generations have been described; as noted various genetic associations, including IL-10, IL-6, IL-1β, IL-23R, toll-like receptors, and epigenetic factors (microRNAs and DNA methylation of multiple genes); multiple infectious triggers as above
Commonly Associated Conditions
- Amyloidosis (late finding)
- Ankylosing spondylitis (10% of patients with joint involvement; not associated with HLA-B5 or HLA-B27)
- Myelodysplastic syndrome (especially in patients with GI involvement) and trisomy 8 (modifies disease expression with an increase in fever)
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