Table 4

Clinical and laboratory features that are helpful to differentiate between A20 haploinsufficiency (HA20) and Behçet disease.

FeaturesHA20Behçet disease9 13 16–19
Disease onsetMostly early childhoodEarly adulthood
InheritanceAutosomal dominantComplex inheritance pattern with familial aggregation in up to 20% of cases
FeverRecurrentUsually absent
UlcersMay heal with scarringUsually no scarring of oral ulcers
EyesSevere ocular disease

  • Anterior uveitis

  • Retinal vasculitis and choroiditis with necrotising inflammation

  • Posterior or panuveitis

  • Recurrent superficial retinal infiltrates resolving within days without chorioretinal scarring

  • Peripheral retinal occlusive periphlebitis

Gastrointestinal(Bloody) diarrhoeaIsolated abdominal pain*
MusculoskeletalMostly polyarthritisUsually oligoarthritis
Erythrocyte sedimentation rate/C reactive proteinElevated, especially during disease relapsesOften normal
Autoantibodies
Autoimmune features		Low titre, fluctuating presence
Systemic lupus erythematosus-like disease and other autoimmune features possible		Usually absent

  • *Gastrointestinal involvement in Behçet disease is usually mild and consists essentially of abdominal pain or discomfort except for patients from Japan and Korea.