Hypocomplementemic urticarial vasculitis syndrome in identical twins.

Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a syndrome of recurrent urticarial vasculitis, arthralgia/arthritis, and hypocomplementemia. Angioedema, ocular inflammation, glomerulonephritis, and obstructive lung disease are other clinical findings. Although the etiology of HUVS is unknown, its resemblance to systemic lupus erythematosus (SLE) suggests a similar pathogenesis. SLE is known to occur in identical twins. This is the first report of a pair of identical twins with HUVS. Concordance for HUVS in identical twins suggests that the pathogenesis of the disease involves abnormal genetic immunoregulation.