Drug acetylation and expression of lupus erythematosus.

Acetylator phenotype was measure in 58 patients presenting to a skin clinic with discoid lupus erythematosus (DLE) and in 51 normal healthy subjects. Twenty seven of the patients with DLE were found to have evidence of systemic lupus erythematosus (D+SLE). Frequency of slow acetylator phenotype was 58% in all DLE patients, 52% in those with D+SLE and was no different from the 57% in controls. The distribution of acetylator phenotypes within the groups with DLE and those with D+SLE was similar to controls. Severity of DLE was assessed as number of skin lesions and median lesion count was 11.5 in slow acetylators and 10 in fast acetylators but in D+SLE median lesion count was 22 in slow acetylators and 12 in fast acetylators, and there was a significant inverse relationship between lesion count and rate of acetylation; scores for systemic involvement showed no relationship. We conclude that there is no difference in the frequency or distribution of slow acetylator phenotype between normal subjects and patients with DLE with or without SLE but that actual rate of acetylation may determine severity of expression of the disease in slow acetylators.