Antinuclear antibody-negative systemic lupus erythematosus - how common?

A review of five years' DNA-binding antibody results in a routine service laboratory revealed 38 patients who had high DNA-binding capacity (DNA-bc) but no antinuclear antibodies (ANA). On retrospective case note analysis, 22 patients (58%) were thought to have systemic lupus erythematosus (SLE), although only six (16%) fulfilled the preliminary classification criteria of the American Rheumatism Association (ARA). Our findings indicate that ANA-negative SLE is commoner than generally realised and lead us to recommended the measurement of DNA-bc in every case where clinically appropriate.