Drug acetylation phenotype unrelated to development of spontaneous systemic lupus erythematosus

To ascertain if a genetically determined slow drug acetylation rate is correlated with the development of spontaneous systemic lupus erythematosus (SLE), as it is in drug-induced SLE, acetylation phenotypes of 27 patients with spontaneous SLE were determined after administration of dapsone. Thirty-three percent were slow acetylators, 63% were rapid acetylators, and one was indeterminate, a distribution not significantly different from that expected in control subjects. Among 4 pairs of first-degree relatives, all of whom had spontaneous SLE, 7 of the 8 individuals were rapid acetylators. We conclude that people who are slow acetylators are at no greater risk for developing spontaneous SLE than are rapid acetylators and that the slow acetylation phenotype is not correlated with familial SLE.