Adult onset Still's disease is recognized as an adult variant of the system
ic form of juvenile rheumatoid arthritis, whose disease-predisposition is s
till debated. On the other hand, the association between HLA subtypes and s
everal groups of seronegative arthritis including psoriatic arthritis has b
een well documented, This report describes a family where adult onset Still
's disease In a young man and psoriatic arthritis in his father were seen.
Both patients were HLA-B39-positive, which was likely playing important pat
hogenic roles in the latter case. Clinical and immunological aspects of HLA
-B39-related inflammatory diseases are also discussed.